So back in the good old days I use to sketch, a lot. And I always wanted to take those sketches and somehow make them all "professional" and such in Photoshop but never had any luck?

So here's a couple examples of old sketches I would love to touch up on:

http://img.photobucket.com/albums/v1.../TheCrew-1.jpg

http://img.photobucket.com/albums/v1...Dayoukor-1.jpg

Currently I have a Photoshop CS4, if anyone can point me in the right direction or even just a place to start it'll be greatly appreciated