Don't be cheap. As they say in life, you get what you pay for. At the end of the day, remember that it's the art that you want, not a bargain.
Don't go to just any tattoo shop. If you don't do your research, you may end up with an artist who does poor work.
Don't tattoo a person's name on your body. Not even your child's.
Don't leave a tattoo unfinished. Save up and make sure you can pay for the full tattoo at the outset. It is not cool to walk around with an unfinished tattoo.
Don't get a tattoo by a random tattooist. Even if you're on vacation and the tattooist is on the beach. Not a good idea.
Don't take tattoo aftercare advice from friends. Get your advice from a reputable tattooist.
Don't get a tattoo from a friend. Letting someone practice on your body is very kind of you, but it's a recipe for disaster.
Don't get a tattoo while intoxicated. Although it's unprofessional, some tattooists will do the work as long as you pay. Don't take anything that will cloud your judgment or delay your healing, or you'll be sorry.
Never tell the tattooist to do whatever they want. You are the one who will wear it, so think for yourself. If you see something you don't like while they're working, don't wait to say something. The mess will only get bigger and more difficult to fix.