The tips and ideas in this post are mostly aimed at microstock [2] photographers / image creators, and for the most part are ideas for promoting work, your profile(s)/website(s) and selling more images...
1] Only upload to the top sites,
You might want to upload to some of the up and coming microstock sites [3] to evaluate your earnings, but in general it will take a lot of your valuable time which you can use more better elsewhere. But always keep your uploaded images ready for submission to other sites as the market changes will will find yourself wanting to upload them again elsewhere.
2] flickr flickr flickr
You can't deny the fact, millions of people are viewing flickr images right now. Some of them should be viewing your images, some of them should be viewing your flickr profile, some of them should be getting in touch to buy your images or following a link to your microstock collection. I have several flickr accounts for different aspects of my work (not all of them stock), both free and pro accounts, I can see from the stats that viewers not only come from flickr but also from search engines. Be careful, and keep the commercial aspect subtle with just a small link to your commercial images on your profile, flickr don't like to see all your photos tagged with "buy me, buy me, buy me now...."
3] Create a blurb book for self promotion
Only if you can create something that looks professional, If so you will earn some valuable 'authority' points, you won't quite be able to call yourself a 'published photographer' but people see your name on a quality, arty looking coffee table book that they can buy for $50 and they will start thinking a little more of you as a photographer. It is also a useful thing to show anyone who asks you in person about your work and what you do.
4] Iptc [4] Keywording
Probably the best time saver I can suggest, embed your keywords into your images [5] and be able to find and upload them easily.
5] Up-Sell your best images
This might not be for everyone, and it's a real time sink so not for the 'time poor' but having your professional quality 'non stock' images on photographers portfolio site [6] with a higher price tag attached might earn you a little more cache in the photography buying world. It's an outlet for landscapes, fine art and 'extended license' materials that normally do not sell well as microstock or garner a fair price via a microstock license.
6] Photo your family
It's pretty common to find when talking to a microstock photographer that their images that feature people are often their own kids, family or friends. Of course not everyone's family will make good models, not because of their appearance, but the way they act in front of the camera - some people just don't make good models. At the very least it's a good way to practice your portrait/people photography skills without hiring a professional model [7].
7] Keyword Properly by Planning
Yep, keywording again, keywords are key has become a bit of a stock photography cliche, but it is true. Have a series of steps that help you keyword your images efficiently [8] to maximize sales.
8] Write titles and descriptions that sell.
Example Title: Barbados, Description: Sunset over a beach. Thats a pretty unexciting example of how to title your photos, use a little sales blurb e.g. Title: 7 Mile Sunset, Description: Beautiful evening sunset over the seven miles of golden sand at <beach name> in Barbados. (I have no idea if there is a 7 mile long beach in Barbados, and obviously the description must be true for your image) This titling business allows you to paint an idea is the buyer's mind, microstock or fine art it works just the same to clinch a sale once someone is looking at the image and thinking about clicking 'buy/download') read more [9]
9] Give some images away.
Ooooh I can hear steam hissing out of some peoples ears right now, and cries of "but you're undervaluing stock photography and yourself". I'm not saying you give all your rights away, but you can provide your images in return for an attribution, so gaining thousands of pairs of eyes on your photo and your name, it's a valuable advertising source and in some cases it can become viral marketing with the right image and the correct distribution. I'd suggest only giving away lower resolution versions of your work, or perhaps only giving some/all of your rejected images, also keep these collections completely separate from your professional profile and marketing so as not to undermine credibility, use a cool sounding pseudonym/nickname for this. The type of people who search for free images are also in the market to pay just a dollar or so for some of your commercial work given the right persuasion. Related article: about free microstock images [10]
10] Show off your work with some free wallpapers. 
There is still big money in wallpapers / desktop images and screen savers. They are a great place to add your self-promotional message - keep it subtle, just a small printed message, or perhaps just your signature and URL of your website / profile space [11]. Either distribute these from your own site, or / and (even better) upload them to one of countless websites that allow visitors to download them (this will get you great exposure!). The advantage of a desktop background is that you can license it for use only as a desktop background, so if someone likes the images and wants to print it or use it on a website they will have to buy it. (there is a risk that they will just steal it, but that is true of any image that you place online, including images that people have paid for and then another person has come along to their site and "right click - stolen".
11] Give away a screensaver of your best images
Similar to the above option, but it's a little harder to make a screensaver (a desktop wallpaper is just a JPEG image, but a screensaver has to be a special executable and different for Mac, Windows and Linux. There are lots of free tools that will help you do this, but I'd recommend paying for some software ($29-49 is typical), this normally allows you to include your own promotional messages and removes limitations or ads that the free versions of the software invariably have. Look for software that has a free version as well as a paid one, try the free one first and if it works for you you can see if there is a need to buy the paid version.
12] Create some templates and css styles ('pimp my profile')
This one is very involved! Create some templates and css styles that people can use on myspace or similar sites, 1000's of users who know little about web programming are searching for code snippets to cut and paste into their profiles and blogs, If you're a dab-hand with web design and scripting or can set-up photo sharing software to create BBcode to do it for you then you could turn myspace into your viral marketing machine. Allow people to use low resolution images for free, and include a simple non-intrusive link within the code so that if a visitor viewing the image clicks it they are taken to either your microstock site profile or to a site where they can download code to add to their own profile (and of course they will see more of your photos and your affiliate sales links).
13] Start a written blog of your work
It could be just a journal about each of your shoot, journeys you have made, places you have been, some tips that other photographers might be interested in, a commentary on how you created some of your more unusual images. Or even better from the point of view of selling microstock... more on setting up your own photography blog [12].
14] or Start a photo or image blog (a photocast),
A new image every day is not too hard to achieve, and you can upload images in advance and have your blogging software display them at the right time. Over time you will create an archive of 100's of images, all have their own page with description and keywords, and search engines will love it, especially for users who want images of a very specific object or place. I have found that the more obscure and specialist the image is the more hits it gets. Each hit might just be someone who wants to buy. make it easy for them to do so, either concentrate on selling it as microstock, or use it as another stream of income in selling prints.
15] Write some Feature Articles
Write a guide or story and include your work and syndicate them online or submit them to magazines / newspapers. It's likely that you have already done some photography that is related to a hobby you have, or have taken images while travelling or at a sporting event, so write a feature, fictional story or a review of something. Remember your images earn nothing if no one sees them. Try a service like ezinearticles.com [13] to syndicate your story or better still get in direct contact with a website or blog and offer them an exclusive story.
16] Shoot only Images that Sell:
Read the lists of "images we want and images we don't want", most of the stock sites have these lists. Your images might be perfect in every aspect but if they do not tell a story or emote a concept from business, family or life etc. then they will probably sell little or not at all. Sure, you can take a picture of some cookies on a plate, but do it while you are shooting a scene depicting 'cosy family life in front of an open fire' or 'over-eating and obesity in the young population'. Tacking difficult subjects like 'overcoming a disability' 'racial discrimination in the workplace' or 'stress and bullying' are much more likely to be noticed and sell than a plate of cookies that anyone could shoot after a trip to the supermarket. Everyone else has already taken cookie pictures so save yourself the time and shoot fresh, saleable images. Most popular microstock searches [14]
17] Get software to automate things.
There are various pieces of software to help you in streamlining your uploads and save you time sat at the computer, for more on this see workflow optimisation [15]. Getting images from lens to stock photo agency fast and efficiently is important, if it takes you three hours to do each picture then you will lose interest and become a microstock failure.
18] Setup your own website
Drive more buyers to your images. It can be time consuming but running your own individual portfolio site to attract new potential buyers and direct them to your images for sale is a great way to grow your sales, and really makes you look like a professional entity. See step 5 on this post [11]
19] Keep the faith
It's easy to lose faith when you look at all those great photos out there, or are picking your way through dozens of shots that you took that didn't come out quite as well as you had hoped. You can feel that everyone is taking photos and they can all do it better than you. Stop for a moment and have a look at some of your best photos, the ones which you have selected to be sold or are already selling, it can be a very uplifting experience to look at a directory full of your best work. You'll realise your work stands up quite nicely, in its own way, in amongst 'all those other photos'
20] Be inspired
If you are not losing faith (above) then the other thing that can often be in short supply is creative inspiration. Everyone has their own place, I find a trip to the local book store leaves me bursting with ideas I want to go and try, but creativity can be as close as the packaging in the kitchen cupboard or those magazines on the coffee table.
21] Backup Often
You might not think it will help you sell more images, but backing up regularly and keeping multiple backups at a different location (with a relative, friends house, at work etc.) will certainly guarantee that you will never end up feeling like taking your own life when a hard disk disaster happens... and it will. I just switched my machine on one morning and nothing, a whole weekend of trying repair software and restorations (I used to work in IT) left me with no choice but to reinstall on a new disk from a system image taken about a month earlier. With that and the fact that my images are always duplicated to another machine meant that I did not lose a single image, it just cost me 2 weeks of time tediously resorting images I had already sorted once already, I don't want to think what would have happened if i had to rebuild my system from scratch. backups for photographers [16]
22] Buy a mini light-room or make your own out of some sheets and lamps
Make taking photos of isolated objects on white backgrounds fast and simple. Without it you will be spending way too much time cutting things out in photoshop, or you will just end up avoiding one of the biggest sellers on microstock sites, 'stuff on white backgrounds'.
23] Join the community
Put a little time aside each day to contribute to microstock sites that have forums, and related bulletin boards etc. answer users questions and suggest new ideas, and of course you will be including that url of your profile space or stock site affiliate link in every post you make... I MAY gain you some photo sales, it WILL l give you a warm fuzzy feeling that you have helped someone today. I do this when I'm feeling 'lacking', I often come away having read something that inspires an idea and picks me up out of my 'hole'. Microstock blogs [17] and microstock forums [18]
24] Stop using Photoshop! (quite so much)
Stop taking pictures that need time consuming photoshop work. Use a low ISO so you don't need to remove noise [19]. Clean each item you photo thoroughly so that you don't have to clone stamp out specs of dust. Light your subjects properly so that you don't need to tweak the exposure after.
25] Tomorrow is never better
Oh we all know that procrastinating is bad, and that's why we all do it. Tomorrow will never be a better time to go and take photos. Look at all your best selling work, you will find you took your best sellers while you were, well, 'taking photos' (not a surprise really), None of your best photos were taken while you are planning or waiting for the best time to go and do it. So go, do it.
26] Marketing Genius
Who ever said that being a microstock photographer was about taking pictures. To be successful at microstock you can 'get away with' being an average photographer, but you 'must' be a marketing and networking master. Think like your customer, watch design and market trends and monitor records of how your images sell. Try reading our marketing guide [20] for some ideas.
27] Read this site
Fine, I hear people groaning at my blatant self trumpet blowing, but we do have a great collection of tips aimed specifically at photographers (of all levels) selling photos on microstock sites.