Read the article.  Good stuff.  We've also been discussing it quite a bit on the forums lately.

I still think there are three key factors that need to be balanced to be successful in microstock: quality, quantity and variety.  If you upload a high quantity of the same subject matter, you cannibalize your sales.  If your quality isn't up to snuff, you won't sell a thing.  And just as important: you won't grow if you're not diversifying your portfolio.  You'll simply be replacing your prior shots with new shots on the same subject, and you'll just be stealing sales from yourself.  When I'm considering what to upload each night, I scan what I've uploaded lately to make sure I'm not doing anything too similar.  It seems to be working.  Old shots continue to sell, and new shots also do well.

Great article, I hope I am considered a Quality...although as time goes on some of my earlier work I would say might be Quantity work...hahahahaha