I\'d never thought of pencilling it in first, doh!
I tend to create a grid using a brush, but with paint severly watered down as then any slight wobbles dissapear when you start fleshing out. It also gives decent practice for going back and blacklining once complete.
However, I\'ve recently been having trouble on some heavily flowing robes in getting the grid to work, so I\'ve been painting individual squares and I\'ve found that an easier way of sticking to irregular surfaces, even if it does take bloomin ages!