I am not sure how everyone else does it, but for the few leaves I have extracted, I use my Macro feature on the camera. That gets a good closeup and the rest of the background is somewhat blurry. That helps me out, since extracting is not my favorite thing to do.
I use the lasso tool too in conjunction with the magic wand to get a pretty close selection of what I want. Since I am not good with the eraser tool, I generally contract my selection by a few pixels to get rid of any little bits I missed.
I am sure other people have their favorite methods too. I use PhotoshopCS2