There is a learning curve that requires time and money...nothing is free and/or comes overnight! Just remember that any trade/skill needs its dues! Even for a hobby...
Find a CURRENT pocket watch movement still ticking. It is standard to recommend/use an ETA 6498 or its original version in UNITAS, available for about $50. Then you can move on to smaller watches. Seiko's 7S26 and family make good starting watches too but they are smaller: 16 vs. 11 1/2 lignes respectively. Also Asian/Japanese watches are not always the Swiss type so expect to deal with a new concept...in principle it is all the same, in design there are plenty of differences.
Pitfalls/techniques that need to be solved/addressed immediately while learning are: tweezers manipulation/skills, gentle touch, parts management and manipulation, hairspring skills, mainspring skills and definitely all sort of springs manipulation, jewel care and handling, assembly and disassembly techniques, cleaning techniques, lubrication techniques...there is simply a lot to learn (those are just the basics) and plenty of room for improvement...and don't forget your tools maintenance either or the case parts and restoration if you are casing or working also with a "second hand" watch. Those parts include the dial, hands, bezels, gaskets, etc, just to name a few. The list goes on and on for everything movement/watch learning curve.
IMHO