Isaac Gube has some recommendations on how to improve your photography skills in DIY fashion:

I've written a short introductory article for eHow entitled "How to Make Money With Your Digital Camera (Selling Microstock)" -- take a look here. It is a short overview and I'm interested in any feedback you may have -- either to improve this article or for ideas for future articles you may be interested in.

Excerpt:

MacWorld has seven tips for would-be microstockers (see below). It's always helpful to read other people's summaries of the things that they find important. This is a decent list of basics.

1. Understand how it works: "...Selling stock photos is not easy money. It will take time to build up a decent sized portfolio (at least 100 pictures) before you see any sizable return..."
2. Think like a designer: "...Designers want photographs with ample amounts of uncluttered negative space so make sure you leave room for a headline or other text..." [Click the title above for more]

Here are a number of news items about Shutterstock's recent acquisition of BigStockPhoto. Each has an excerpt and a link to the full article.

Photo District News: Microstock Site Shutterstock Acquires BigStockPhoto

It's interesting to look back on the microstock experiment I started a few years ago. I have been quite lazy this past year about uploading anything--and expected my sales to dry up because of it.

If you're an artist, create vectors--they sell well and if they are sufficiently detailed, some microstock sites will tag them as more expensive downloads--meaning more money to you. Selling vector images at Shutterstock means working within the (essentially) all-you-can-eat package--which can also mean many, many downloads.

A number of microstock sites offer free downloads as a way to give you a taste of the types of images and image quality they offer. It's not a bad idea for designers on a budget to peruse these offerings now and then. Most notably, Dreamstime has a rotating selection of seven images available for free download at any time. Log in to the main page and look for the "More Free Photos" link to see all seven.

Make sure to look into referral programs on the various sites. Many of them will offer rewards for users that you refer to the site either as photographers or stock image purchasers. You can send your referral link to interested people by email or include the link on your personal website. Shutterstock and Dreamstime are particularly good for rewarding successful referrals.

If you want a constant (and constantly growing) revenue stream from microstock--upload new images regularly. Many of the sites sort images in a number of views from newest to oldest by default, so that designers who are regulars can find the fresh photos and vector images quickly. This means that the more new images you keep in front of them, the more likely sales will be. As well, the more images  that you have in your library, the more statistically  likely they are to show up in keyword searches.