You need a lot of the same shopping/vetting skills that you need in any other part of life.
"Eternal vigilance" is kinda "the price of getting through the d@mn day" any more.
Personally I've seen a fair amount of similarity between what I've had to do to get my car taken care of and what I've had to do to get decent medical care.
I even had one excellent shop, which I researched the cr@p out of before using and then happily patronized for seven years, have one $h|tty employee try to rip me off for a couple thousand dollars when I was in a very vulnerable place. The guy was like a caricature of bad 1950s car mechanic, and they knew it, but for whatever reason couldn't/wouldn't get rid of him -- so they made him a floater, which from the customer's POV just meant that you couldn't avoid him by going to a different branch, he could crop up anywhere bwaaaaa.
But I got through it, because I was paying attention and took care of myself. (I mean, there's always also luck involved -- if the @$$hole parade is long enough, you might lose out, but usually if you keep pushing you'll get to a decent solution. Decent car mechanics are my heros.)
Among other things, ask a lot of questions and pay attention to HOW people answer. If they try to frighten you or make you feel stupid -- or if their answers are too vague or too arcane to understand -- that's all the red flag you need to walk away. (Note: arcane language does NOT mean that someone is a big-ass expert; it just means that they've failed to communicate with you; there's nothing impressive about that.) I look at reviews (with a big grain of salt), and whether they have, for example, ASE certification or NAPA affiliation or a good BBB rating. ... None of these is a silver bullet, but in combination they can improve your chances of success a lot.
In the early 2000s I had a book titled something like The Women's Guide to Car Buying, but by now I'm sure there's a million resources like that online. (And it's not like guys don't have to learn this stuff too.)
It's an S-ton of work and stress with no guarantees. If you want to and can get someone else to do it for you,
\_(**)_/ ... but it shouldn't come down to your genitalia. (And if "it's a sexist field" was a good reason to "get a guy to do it for you," then half the people on this forum would still be barefoot in a kitchen somewhere -- the worse the problem is, the more women should be learning to cope with it.)
Here's to all the independent people on this forum, and all the skilled people who share their knowledge so generously.