When I do an illustration - I paint my backgrounds , scan them , and collage and draw in Photoshop with my pen / Wacom Tablet. I rarely draw my line and scan it. And I never paint the line on top of the background painting. Much safer to do it separately. Today when I was painting for a show next fall, trying to get my creative juices going, I decided to take some older underpaintings and PAINT MY LINE RIGHT ON THEM. WHOA. Scary. I made a deal with myself - NO fixing or collaging in Photoshop. Yes, I ruined some paintings, but I sure had fun aand got some good stuff while I was at it.