What should I look for when buying a used car?

(Adulthood fail.) This weekend my clunky old car died for good and I had it towed to a salvage yard. That was my first vehicle and I got it for free from a relative, so I’ve never purchased a car before. I don’t have a ton of money at the moment and my credit is pretty bad, so I doubt financing is an option. Anyway, I don’t want to end up in one of those situations where someone else finances for me and I fuck up on the payments. I just want to buy a cheap car that’s somewhat reliable, ASAP. Where I live, there’s no public transit.

People have been giving me varying advice about this, like:
-if buying from a private owner, make sure they have a clear title (they do not owe money on the car)
-get an inspection from a mechanic before you buy
-it will be difficult to find a reliable car for under $2000
-make sure the dealer is trustworthy.
-focus on saving and finding the best car possible, even if that means being without a car for several months.

Any other advice? Realistically, I can’t even afford $2000. My budget is more like ~$1000. I must be the most irresponsible person ever, because I didn’t really expect this to happen when it did and didn’t save for it. And obviously, old cars break down. It was inevitable.

I have an uncle who is mechanically-minded and might be able to help me inspect potential cars. But I don’t really feel comfortable asking anyone for money. I want to focus on a solution and handle this myself. Is it crazy, thinking that I can find a car in my budget? Should I suck it up and save up for a few months, then buy a “real” car?