Possible reasons to regret a tattoo
1) Ignorance: Sometimes people decide to go get tattooed without doing research first, just because someone like a specific artist does not meant you have to like the same artist too. Someone might think that a tattoo done at someone's backyard that costs twenty dollars might look good in their eyes but that does not mean it has to appeal to everyone.
I've seen people who like certain styles, designs, artists, etc. they see in the magazines and they wish they could have something in their body that looks as good as what they see but never go for it, they decide to stick to the basics and after they get the work done they still wish what they got looked as good as they one they saw in the mag.
Remember this
The basics on getting the best tattoo are easy
a) Do research: Don't go for the first tattooer you cross paths with, you have to like their style, it really has to be appealing on a high level. If you look at a tattooers work and you really think looks good enough (magazine appeal), go for it.
b) Hygiene: That's one of the most important to have in consideration. Tattoos do get infected and the scar it leaves behind is even worst. Most tattooers have knowledge on how important hygiene is regardless of the size of the studio they work at.
c) Appeal: When you're waiting for you turn to get tattooed you want to feel at peace, confortable and confident that the work will come out good, at relaxed environment helps a lot. Believe it or not, a chaotic environment is not the best environment to get Inked. I've seen tattoo shops where people are screaming, yelling, using foul language, sexually explicit jokes and even fighting while having customers and they simply don't realize they're creating a hostile work environment which is not good for them and the customers.
If you go to a tattoo parlor and you don't feel confortable the best thing to do is leave. Reputable shops make sure that thier customers are confortable being in an appealing environment, also most reputable shop employees have excellent customer service skills (who knew!).
d) Customer's Health: If you have a health issue that concerns you at the time you're about to get tattooed make sure you get advice from the artist. He or She will be open about what's best, your health comes first.