I agree with a lot of what @Daidough said.
Made the mistake of wanting a tattoo from 16-18, walked into the first shop I saw in a little city centre after college one day and got myself a tattoo on a whim. I wouldn't recommend doing the same, regretted it for years and took me a long time to find an artist good enough to begin covering it up with something I liked.
Definitely worth doing some research and looking through a good few potential tattoo artists to see if their style matches up with the design that you want & checking the consistency of their work also.
I will say though, once you get one you'll get proper tattoo fever and want a load more after it. Ruins the bank account