How do i get a better tan ... ?

Okay, I'm going on vacation in like 3 weeks, and I totally want like, a really great tan! I'll be outside like pretty much most of the time ... and I'll be in the water like loads! ... and I'm totally going to be wearing like my bikini ... but I really want a perfect tan! ... like totally as dark as poss! but I don't wanna be wrinkly when i'm older so i don't really wanna use tanning oil ... but any suggestions welcome :D! thank-youuu !!!!