Most locksmiths are one-man-bands, and will do business (farm out calls) to other licensed locksmiths. In a small town, I would suggest working for a hardware store where they make keys and sell locks to get better acquainted with these things.
I know my Ace Hardware store has an employee on staff who happens to pick house locks if a customer should inquire. I'm sure in an informal situation as that, one might befriend such a casual locksmith and learn along side him. I don't know if apprenticeships for locksmiths exist these days, but then again, I don't live in Canada.