Flip it!

This is really important, flip your drawing!

After finishing the sketch, flip.

After laying out colors, flip.

etc. etc. flip.

Flipping gives you a new view of your drawing/painting, and what might seem OK to you while you're immersed in drawing, can actually be pretty crappy to an onlooker, so by flipping you make sure to kill any distortions and malformations in the drawing. It may even be better to keep drawing on the flipped image then flip back after reaching a milestone. (which also gives you an action point <= D&D geekstuff)

I've made myself a custom shortcut for this:

Ctrl+/

It's one of the only keyboard combinations that are free by default hehe.

Have fun!