Long time from drawing/illustrating, and its good to be back.
Much of my artwork is done 100% in Phtoshop with some work with a pencil preliminary drawing. A basic sketch for the pose scanned into photoshop and the layers built up on the scan until none of the original drawing remains.
As with any practice, techniques improve with practice and im again learning much about photo shop once again. But regardless of any software or medium you use, my main advice is practice and always aim to push your boundaries. Discovery is an active part of learning. Good luck out there!