I'm cleaning up my favorite illustrations today so I can take them to a printer on Friday and get some nice prints for conventions. Here's an example of the kind of tweaks I do last-minute:
That lake illustration from last week: I really liked it, but it lacked depth and something about the composition was off (the ripples are out of perspective, too, but I didn't mess with that).
I added a lot of shading on the rocks, water, and some darker color at the edges of the sky, made her coat darker, and made the tree line fade to gray in the distance; all attempts to draw the eye to the center of the picture and make things look more 3D. I fixed some shading I didn't like on her leg as well. And I just like that scarf better in periwinkle. :P