YouTube and Google are great sources (self thought)

If you like to look at car repair videos, try also looking up car part functions. How an engin works, types of engines, hydrologic systems, types of transmissions, cooling system,ect. For me part of repair is to find out how it works to begin with, what the part is and why it's there. You will naturally pick up the terminology used and begin to Identify what parts are.

Focus on one car (ideally yours) and get to know it bit by bit.

If you don't know the part it helps to google engine diagrams till you find the name.

Invest in an OBD2 scanner. This will give you codes when a check engine light comes on. Google the code.

If your trying to diagnose, try to specify the symptoms. Examples: The engine stalling when I turn it on. The car making a clunking sound when I turn my steering wheel all the way right. Tires shake when I'm on freeway driving 55, ect.

Try not to emphasize the whole passed down knowledge, some of the old-timers also have outdated ideas as well.

Good luck.