Here's what I've learned and I know NOTHING.
Don't "ride" the break. Learned that one young.
Change the oil when you're supposed to and KEEP IT FULL between changes.
If the little lights come on, pull off the road and make a call.
When you hear funny noises, don't just turn up the radio.
When something falls off, don't just stop the car and get out, throw it in the backseat and forget about it. Just because the car is still running doesn't mean it didn't need that part.
When it makes sparks, get them fixed - even if you just tie up the offending part. Especially if you're leaking gas.
If the car starts billowing white smoke that has little black bits in it that smells like chemicals and makes your eyes water and throat burn, don't drive it over to your buddy/mechanic's house. Stop immediately and turn the thing off. If you don't, you can kiss that car goodbye and will be on the bus until you can afford a new one. And if that's years, then it is years.
The Rain-X window wiper stuff is more expensive, but if you have a few extra dollars to spend, totally worth it.
If you can afford a better car, buy a better car. It is worth it in the end because they last longer. But don't get a Buick Rendezvous unless you want a car like Christine.
Don't tell your DH that you want to learn to change the oil. The satisfaction gained isn't worth the mess. Learn Spanish (or something else less messy) instead.