I think its a hard trade to truly get in to. If its not going to be a primary job, then go for it. If its going to be the primary job, theres a lot of guys that have been doing it a while, some are good, some are great, many are gun mechanics, replacing parts, and make expensive mistakes, that often wont be made good on. The required equipment to do much beyond very basic stuff adds up very quickly. What can happen often is somebody brings a gun to be repaired, you do the job, then they freak out that it costs almost as much as the guns is worth, if not more. Your time is worth X amount of money per hour, and many guys seem to think you should repair grandpas old gun for the cost of parts (and not making anything on the parts) plus 10 bucks, even when you have an hour or more in it from ordering or making parts, 45 minutes talking about what a great gun grandpas old cheap gun is, then all the yacking when they pick it up. The best shops have a counter person to do the flack diversion, paperwork, and talking so the gunsmiths can actually do their job. That costs money, and it takes a steady business to make it work.
If you can work for a shop that's established, that would be great, though not always easy to get in the door of a reputable shop.
I've looked into it in the past, and talked to many gunsmiths over the years. The patterns seem fairly consistent. If I got into it, I'd want to be with someone like Hamilton Bowen or comparable truly custom grade gunsmith. Not likely to happen without serious experience beforehand.
Best of luck.