In one of my earlier posts on a night out I ended up with 3 Facebook and number closes with a tattoo opener. I have a couple of tattoos already so my question to two girls was "quick question girls, how many tattoos is too many?" It then transitioned to talking about tattoos that have meaning and then I got kino from both of them as they were looking at mine.
In your situation I would look for a girl with tattoos on display (on a night out 50% of women will most likely have them) and then say to her "Hey, quick question, I've just noticed you had a tattoo and so I wanted to ask, how many tattoos do you think is too many?" She'll then either give you a number where you can then say "okay, so how many you got then?" Quickly transitioning to "...and does it/they have any specific meaning for you?" Or she'll ask "why?" at which point you can then explain that you are looking to get some tattoos but don't want to go to overboard and end up looking like a Marvel comic.
Hope that helps
