There are very few good true "mechanics" who understand relationship between parts. Most are part swappers who will just replace parts until it's fixed.

I am my own "part-swapper" if you will. Some things I can do, others, I take elsewhere. Generally, if I can reach it without needing to lift the vehicle, I do it myself. If the vehicle needs to be lifted, I take it somewhere. With the exception of oil change.

I get real good at fixing my own vehicles after about 5 years of owning one. Then I know all the idiosyncrasies of it and will have replaced 2 dozen parts and read the FSM lots.

What I really like about my full sized 1 ton Ford is that it is far easier to reach things than on anything else I've ever seen. The ground clearance is amazing. I don't need to jack it up to change oil.

 

I was in the general auto repair business for years. And in a city of over 200,000 people I couldn't even reccomend a replacement to my customers when I decided to close shop. There are few honest competent mechanics out there. Almost every new customer that came through my door had just had overpriced and under experienced work done somewhere else. As my city emmissions inspector put it"You can make your customers trust you but you can never make them trust mechanics".
Don't just give your mechanic free reign, but don't tell him how to do his job either. If you know that much you should do it yourself. Never pay for more than an hour of initial diagnostic time. If your technician hasn't found a direction by then he probably isn't familiar with your system and you are paying for his education which as a customer you should never have to do. Also don't let them just throw parts at your car to diagnose it. If you authorized a repair and then they tell you that they found some other things wrong too, you better be wary. A good shop will use language that protects them but also helps you make an intelligent decision. If a tear down is neccesary to determine the extent of repairs needed then you should be informed of that ahead of time before you are buried in the thing.
Also if you do find a good shop, let them do everything on your car including routine service. Once they become familiar with you and your car they can take good care of you by seeing potential problems amd allowing you time to work it into your budget. And avoid the bargain franchise joints. Nothing will cool your relationship with your mechanic like seeing a set of midas shocks on your car after he has held your hand and did all the low profit or technical work that required expensive equipment, just to have you ***** out your business to save a few bucks up front.
One last thing, mechanics accept tips too. If you appreciate yours, let him know.