Getting a tattoo is like any other form of personal expression you might choose, whether it's the way you dress, the music you like, how you do your hair, piercings, makeup, etc: some guys will like it, some won't. So yeah, some potential boyfriends will turn and run if they see that you have a tat. But you aren't doing it for them; you're doing it for you. It's just more permanent than most other forms of self-expression.
Your friends have good intentions--to look out for you--but they are generalizing, and basically saying you should do what pleases others. Don't do it. You can spend your whole life trying to do the "right" things to attract guys, but if you do that, you are living for them, not for yourself. Besides, it's a waste of time, because every guy is different, so no matter what you do, some will like it and some won't.
Just do what pleases you. If you like the tattoo and a guy doesn't, there's already a good chance you aren't compatible. If a guy judges you on your tattoo before getting to know who you really are, then he's not worth dating anyway.
Thanks for the question.
I have loads of tattoos; and big ones too. I used to only go out with the kinda of guys who were into tattoos and piercings (think harleys and moustaches) but now I'm in a relationship and very much in love with a clever, nerdy, cute, cambridge graduate, who dresses and looks ultra conservative, and own an IT company. He loves my tattoos, he was never put off by them so you never know. WA is right; the right guy will love you for you, as you are :D
Listen if a man judges you soley on the fact that you have a tattoo then he's not the guy for you. If you want the tattoo, get the tattoo. Don't let your friends decide for you.