In my caricature, I always fill up the hair part instead left it blank otherwise I felt the artwork incomplete.
I found that most of the caricaturists nowadays in the market do the caricature in the event just draw the line without fill up the hair, I would say if you wanted to draw everything in line, provided you know how to control your drawing strokes, otherwise you are cheating!
Thought too many part time students or cheap event people spoil the market, so the market had spoil and you will hardly see quality artworks during event nowadays in Singapore.
No matter how, as long as I got a change in charge, I will to my best ;p