Daria noted quite correctly that, in fact, the pain threshold is different for everyone. It is better for you to start with the knowledge of your body: how sensitive is your skin and how it reacts to the effects of various factors.
Generally speaking, I will start from the most painful places (you can already determine where the tattoo will hurt the most):
Areas with only "skin and bones". I think you yourself understand what this refers to: elbows, knees, ribs, in principle, too, feet, hands, collarbones, and, in fact, the chest too.
Head (+ face). For centuries, I generally keep quiet, this place is considered one of the most painful. And all because there is the thinnest skin. + groin area (sorry to include in the face)
Some areas "adjacent" to the most painful areas. Same shoulders, neck, wrists.
In general, and in fact, the more "meat" in the area that you are going to slaughter, the more painless the session will be. Although, in most cases, this is just an unpleasant sensation, not pain, what happens with surgery. In extreme cases, pain relievers are always available, tattoos also progress.
There are many opinions on where to get a tattoo is less painful. I believe that everything depends on the person, on the so-called "pain threshold". I made my first tattoo on the side of the ribs, many dissuaded me, arguing that this is the most painful place! But nevertheless, I made up my mind and did not regret it. From that moment, I just realized that the concept of pain for everyone is purely individual! And the place, as for me, turned out to be very successful. Firstly, she was not often in my sight, thus she could not get bored in any way, and secondly, in this place you can get a tattoo of almost any size. And thirdly, if suddenly at work or somewhere tattoos are not desirable, then this place is also more than suitable.