that's pretty good! i think when you posterized it you lost some detail in the black areas. If you adjust the curves you can get it a little lighter. Otherwise looks good and that background is pretty cool too.
Thanks You don't need to make vectors to do multi layers just find a photo with good contrast and then use any basic photo editor to crank up the contrast until you can see definitive lines in the shading.
oh ok well if you have cs4 then there are a few tips I can give you. One is the posterize mask in adjustments. Just put that on any photo and it will break it into layers. If I use posterize I'll then tweak it by drawing in my own colors and smoothing lines and what not but its a good guide to start. Layersmagazine .com has great photoshop guides too look for the one dealing with selecting color range. That is great for stencils too.
really like that background thing, feels like i should be saying could use a bit more detail on some bits but for the most part it really works, there is just a piece of hair on teh left that is white and looks wierd and maybe a little more detail to define her thumb