How does one go about getting a new to me car?

For someone who doesn’t know anything about cars, should I go with a dealership or private? If I go either way what questions should I ask? Do I need to bring a mechanic with me? And how does that work? Do I just call up a place and ask them to come see it with me?

And no, I cannot afford a new car 🥲 had a honda civic but now it’s out of my price range.