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]