I've never had many mechanical skills (or patience which is one of the most important) but when I was younger and poorer, it was necessary to save as many dollars as possible: I'd get the shop manual for a used car I bought, read-up on how to maintain it and make minor adjustments......and most times be able to diagnose a problem. Sometimes a problem was more than I could handle, but at least I wasn't a babe in the woods when I took it to a mechanic.
After a while, the saving-money motive was replaced by the sense of accomplishment.....and the satisfaction of knowing that the job was done right (the same reason I do my own house painting and minor repairs: sometimes you can't pay someone enough to do the job right).
'Course, the days of being able to do anything on a modern car are over for me......and the cost of repairs has skyrocketed. The only defense has been to buy new, or nearly-new cars and I don't miss those trips to the repair shop.
Am reminded of my last big problem a few years ago: my '96 Chrysler LHS developed a "clunk" on hard left turns. It started out as an occasional light clunk, but over the period of 3 years progressed to a frequent heavy thud. I read the shop manual, I posted to the Chrysler group and got lots of advice. I learned there was a problem with steering box bushings addressed with a factory retrofit kit. The car went to the dealer and a reputable mechanic innumberable times. All the front end bushings were replaced, the ball joints, the CV joints, the front hubs with bearings, etc. Nothing helped, and if you're thinking this got expensive, your're right. Finally the dealer wanted to replace the struts, mounts, etc to the tune of another $1400 and I drew the line, living with the clunk.
One day I dropped my pen and it rolled under the car, so I'm reaching under there with flashlight in hand and happened to glance at the exhaust system: surprise! only half of the exhaust clamps were there on the downpipes......no end to the clamp or boltsm just the "U" part. So I went to the parts store and bought 2 clamps, installed them and that was the end of the clunk. Certified technicians, indeed!