XD I sign all my complete drawings and finished sketches, I guess. Or at least, I don't remember not signing them.
I don't sign my sketchbook sketches for some reason, cause it's more of a doodle for me and not a finished piece of work.
I sign augi on it and not my real name cause that's my nickname/online alias. Plus, it looks better and is easier to sign.
My sign is in this
http://augipaw.deviantart.com/art/Theo-72974275
XD; I actually don't think my sign actually takes away from the pic. Alone, it's just like this:
Er... the reason I sign my art? Er.. dunno. But seriously, it's retarded when people claim you've stolen something you've drawn. Though, it sounds kinda like an insult yet compliment at the same time. =__=;; That's actually never happened to me.