What kind of picture should I put up on my online dating profile?

I know that profile's with pictures tend to get more attention and hits but I am usually behind the camera, not in front of it so the last picture I have of myself is around 3 years old. I would like to use a current picture but should I put a formal / professional looking shot, a more casual picture but still posed or give somebody a camera and get them to take a more candid photo? I would like to just put a shot up of something i've taken but know its important to have a self portrait so to speak.