I would pick up a older Elgin, Bulova or major brand simply for parts availability, but before you start on wrist watches, I would spend time learning on pocket watches, get a couple working older ones, then just take them apart, clean them and re-assemble them, over and over, until your able to take all of the parts and place them into one container and reassemble it. Because at some point, defecation occurs and your going to have to do just that.
Also acquiring the hand skills working on a larger pocket watch makes transition to wrist watches easier, as the parts are smaller, and can be more frustrating
