First, subscribe to a few of the car magazines, like Car Craft, Hot Rod, Mopar Muscle, etc. They typically have a lot of good tech articles.
Second, what any and all of the TV shows on car work like Two Guys Garage, Trucks, Hot Rod TV, etc. You'll pick up stuff there.
Third, try to find used general repair manuals, like the old Chilton multi-car books that covered domestics or imports for specific years. Read through that when you are in the bathroom or something to get ideas on how stuff is done.
Fourth, check with ASE to see what books are available as part of their certification testing program...not that you would pursue certification (though that's not a bad idea), but the test prep books I've seen cover a lot of the technical aspects of repair.
Fifth, try to get a job at a local indpependent shop. I worked at a couple and really learned a lot. If you have basic mechanical abilities and have good reading comprehension, you'll get a lot of learning done in a short period of time.
I made a lot of money in college working on cars. I eventually got a job as a personal assistant for this guy who literally had 6 cars, all old, and all needing constant attention. I charged him a fraction of what a shop would charge, but still made about $20/hr. I don't work on cars for money anymore, though I try to keep up with technology and do pro bono work for friends and family. The biggest thing is buying the specialized tools needed to work on so many different cars!
Good luck.
