Yes I always sign my art, no matter how crappy it is. I do it to avoid art theft. I sign my full name,the date, and I water mark the crap out of it if it's digital. I know that it makes the art look ugly, but I've seen a bunch of people get their art stolen. There was this one case I remember from a while ago. Someone stole this girl's art and sold prints on ebay. Seeing so much theft I've gotten really paranoid that I'll be next. D: