I mostly advocate for guys to do their own work, start with an oil change and continue investing in tools and knowledge 'till you can do most work yourself.
Here's the problem, so many people are afraid of dirty grease monkeys. On a national basis grease monkeys are revered nicely between lawyers and pond scum for business integrity. This should not be the case. Another guy on this site has put his life, his families life, and the lives and well being of everybody else on the road into jeopardy because he didn't trust his mechanics word that he needed new brakes.
Most techs are honest and well trained.
Yes their pay is based on what you buy from them. So is a doctors but if he tells you you need kemo you take it. The fact is there is enough work that is necessary that a tech doesn't need to be dishonest. It doesn't mean there aren't thieving pricks out there but ask around and you can find good ones.
Living in fear of techs is foolish and dangerous. Learn to do your own work if you can't afford or trust the techs near you. the best way is to arm yourself with knowledge, if you think you are being griffted ask for estimates from multiple shops. Most will at least estimate for free. And you can always ask to be shown the problem, the new and used parts.
And please remember the price of a vehicle does not end with the purchase, it includes maintenance and consumable parts.(brakes, tires, fluids, filters etc.) Notice when the car mags do long term test of vehicles they include additional costs.
Please maintain your vehicles for the sake of your loved ones and the loved ones of everybody whom you share the road with. Thanks