Ah you mean real art! I only do digital at the moment, the real thing is too time consuming (and I suck at portraits too!)
Like the others have said - the likenesses are not quite there yet, but practice will get you there as you obviously have an eye.

Sam's is closer than Dean's, especially the right hand side of Sam's face (as we look at it) and Dean's lips are pretty good. I love the colouring, pastel suits this picture very well.

You should post this on spn-art and supernaturalart on LJ too. I stick all my wallpapers on supernaturalart.