The wiki mentions that he was a member of the original Order, and has nothing between 1981 and 1992. Do we know what he was doing at this time? Do we want to know?
As I can't find a canon answer, and I doubt anyone else can, either, (he's not a very important character) I'll have to say stealing. We know he's a crook - it's stated so many times in the books. Why assume he was doing anything different? Most likely he was stealing, conning people out of their money, and avoiding arrest.