Squats, hip thrusts and glute bridges are the best. Just make sure you maintain the right form, keep your butt back and your back straight at all times when doing the squats. Hip thrusts and glute bridges give your booty a burn that just forces it to grow! Also kick backs activate your glutes quite nicely.
I have concentrated in those exercises for years now and it really gives you a feminine lower body appearence. It's just an amazing feeling when you get past the muscle exhaustion and continue your sets feeling that you are just gorgeous booty and thigh!