Some people can pull them off, and others can't. Don't get them in a part of your body that is prone to stretch marks, etc. And put some thought into what you get... Make it meaningful; don't get something random just for the heck of it. (This is with regards to tattoos). As for piercings, it doesn't really matter... You can take them out whenever you want. I think that some people go overboard, but a little jewel here or there can be nice if it's done tastefully, and works to accentuate nice features of your face or body. Personally, I don't think I'd ever get a tattoo, and I stick to pretty generic piercings (ears, nose)... But that's not to say that I think there's anything wrong with going further. My ex had quite a few tattoos, and was muscular... It made him look a bit tough (even though he's actually a giant teddy bear), and I thought it was pretty sexy. That, and tattoos and piercings can actually be very artistic!
Personally I find that they tend to make a girl less attractive but that's just me personally. I think in moderation some guys like one or the other. I'm OK with ear piercings but preferably would prefer without
earring and belly piercings are pretty, anywhere else is a turn off (for girls). for guys, some look good with lobe piercing. Tattoos on some guys are ok...my guy has a tattoo on his chest of latin words I don't think it looks that good but I haven't said anything to him yet...LOL. I was thinking of getting a girly desing tattoo on my back but that's probably not going ot happen