For those of you who are interested in trying out micro stock photography, I can recommend to try out 123rf . Having dabbled in the frustrating world of micro stock, I feel that their site is very userfriendly, with fast uploading. And once they sell, the pay is generally much better than most other sites. I even had a sale of €35 ones!
They do like to reject images for flat/dull colours, which basically could mean anything. And in general, when i look at my online portfolio, many pictures do look more dull than on other sites, which is very strange. Images should look the same on the same monitor, one would think… So try to tweak your pictures as much as you can for some brightness without distorting your pixels.