Well, I got my first tattoo at 17. It's a shame really. In our area (Washington State) a person must be 18 to get one. Even if their parent consents. My Mom was reluctantly on board. I had designed it myself, had thought on it on a year (a year seemed like a very long time when I was a teen), and had worked for the money.
Well, no dice. Couldn't get a talented artist to do it.
Patience is something I struggle with NOW. Then, it was an * impossibility*. Just not part of my personality. So I found a lad who was an apprentice in a reputable shop. He'd only tattooed a few people and not very well. He fudged the paperwork, I went behind my Mom's back, and got the darned think put into my skin.
The work is just awful. I still like the design, and I like what it represented to me then and now (it's about rebirth, and the relationship between light and dark), and think I could carry it throughout my life. I hate the way it looks.
So now I am (not successfully) saving up money to have it done over, by someone with skill.
14 may or may not be too young depending on many, many factors. For me, 17 was too young. Simply because I couldn't find a proper artist and lack true patience. 14 would have, for me, been way too young. I didn't know who I was at that point. That's not true for everyone. And, of course, our cultural norms vary as well.
Piercings? Oh heck. I've had my share. I pierced my own ears (high pain tolerance and an adolescent drive towards suffering - *sigh*). I pierced my belly button. I've had both sides on my nose pierced too. At this point, my tummy piercing scare + pregnancy looks pretty awful. And now I'm just not a fan (for myself). The only piercing I keep are one each in each ear. I don't have scars on my face or ears. So that's good. It was fun, and temporary. No big deal in *my* book.