re: Big Al Star Wars fark...

I know you were asking him but assuming you're using photoshop, the move is to use the smart selection tool to get it close. Then you go to the selection menu and select what up until photoshop cs6 was known as "refine edge" tool, but in the current iteration of photoshop cc, it has become the "select and mask" tool.

This is where you refine your edges. You can feather, expand and contract, adjust smoothness, contrast, etc.

It used to be a whole lot more complicated before about cs4 or so.