The raw workflow
For those who haven't yet appreciated the benefit of RAW format I advise to take a close examination of the argument. I am one that in my first year and half in microstock shooted just plain jpegs. Then find out that shooting in RAW and including it into my post-processing workflow was something incredibly useful.
Since then I haven't looked back anymore (jpeg what? :-) and I assure you that my acceptance ratio was improving enormously.
RAW format allow you to better correct, not only the usual mistakes (blown highlights or undersposure), but especially noise and sharpen your images as you can only dream after the image has been processed by the camera and output in jpeg or tiff format.
Here you can find some useful articles about raw image processing: