Fewer and fewer people do their own car repairs. Some still do though. That is the way I started. Without “google” I might add. The public library supplied most of my reference material. There weren't any filmstrips showing me how to change my brake shoes on my VW Beetle. There was a Clymer manual at the public library though.
Doing your own repairs also requires tools. Unfortunately there is not a library of tools. Automotive tools are very specialized. More so than ever. As I always thought I wanted to fix cars for a living I bought tools as I needed them. It increased my repair costs but it meant one day I could fix something else with those tools and maybe make a few dollars in the process. I am roughly forty five years in and I guess it has sort of worked out as I planned. I still have and use Craftsmen sockets and wrenches that I bought when I was sixteen.
I am always excited by someone who wants to learn to fix their own vehicles. One thing for sure, you can probably find a “YouTube” to show you how. I am not saying it will always show you the correct way though.
Occasionally a customer will bring their vehicle to us after attempting, unsuccessfully, to solve a vehicle problem. They will state the problem followed by a litany of parts they have replaced. They will likely iterate the amount of money they have already put into their attempted solution and qualify it with not wanting to spend significantly more money.
In most cases the parts replacement process is much more costly than professional diagnostics. The parts replacement approach placates the perpetrator though. “It would eventually have needed a new radiator anyways, even though it still overheats. I got a good deal on the radiator on Ebay.”
Diagnosing and repairing a problem that was already unsuccessfully worked on usually requires significant backtracking. Just because any given part was changed does not preclude testing that part over again. Does that part meet the manufacturer's specifications? Does it even work? The market is rife with substandard parts.
Was the part installed correctly? It is easy to make a mistake installing a part. It is even easier to make a mistake when you lack the correct tools, accurate information and experience. One tooth out on a timing belt and your engine will not run correctly. Two teeth out and maybe it won’t even start. Three teeth out and the result could be a destroyed engine.
If you want to fix your own vehicle I applaud your efforts. Do not be discouraged by failure. Remember though that when your mechanic takes over he will likely check your work.