You want to go to the industry of car repair, you must start from the professional, of course, you will repair excavators, bulldozers, the basis of learning to repair the car, the engine system, of course, will be very easy to learn, but the other parts of it, you need to be further careful to learn
As you said, if you really want to fix the car, and can be in a relatively short period of time to learn to do it, it can only go to the auto The only way to maximize your experience is to go to an automotive store where you will be exposed to a variety of problems in practice and solve them one by one.
General 4S store learning, feel the threshold is higher, after all, that is a brand, they want to be able to work, and can save money, you hold learning and go, not quite right.
It is recommended to start from a normal garage, after figuring out all the common problems, then move to a large repair location like a 4S store to upgrade.
Everything should be gradual, from easy to difficult this process is necessary to go through, so a little bit of what you learn to absorb and digest, turn into their own use.
Can't be in a hurry, be patient and learn it well.
Wish you success!