Hey amat. I'm not sure if this will be too helpful, but here goes...
I've got 3 tats (it'll be 4 in a couple of weeks), they're all pretty big, except one. I'm 25, I got my 1st one at 23 after wanting one since I was your age (Christ, typing that made me feel old). A rule of thumb I've always followed when deciding on what to get and where to get it - is to wait for about 2-3 months (sometimes more), and if I still want to get it, I go and get it done... All of mine have personal significance to me. My first one was bought for me by my mom, the second one was something drawn by my best friend, and the third one was a tat in memorial to those killed in WW2 (something I have a massive interest in). The fourth one is going to be a tribute to my mom who passed away about 1 1/2 months ago.
I love tats and they're very addicting in their own way, but never, EVER, get anything trendy (like the tribal shit), some of my friends have those, and they almost always end up getting them covered up... Don't get some flusey's name either
My mom hated the idea of tattoo's until I got some, and afterwards, after I explained my reasoning to her, she loved the idea of them and was even planning to get some of her own, so I wouldn't worry too much about what your dad thinks, I doubt he'll care all that much.
I think I read that you're thinking about getting one on your stomach, from what I understand that hurts like fuck. I have a friend who does tats for a living and he has confirmed this. But it doesn't hurt that bad, the one on my back took 5 1/2 hours and it only really hurt during the outline, and afterwards it feels kinda like a sunburn.
Sorry for the long rambling post, hope it helps.