What kind of ballet shoes should a 17 years old female beginner get? Also any tips?

If you are just starting ballet you will not need pointe shoes for awhile. A good idea is to start off will a leather or canvas flat slipper with a full sole. Split sole shoes are much more popular with most dancers, but the best choice to start with is full sole because it makes your feet stronger when you are doing your tendu exercises and strong feet are essential to performing other more advanced moves well in ballet. Most dancewear websites give sizing info for each different shoe so just follow them, I've bought shoes that way before and been fine each time.