My favorite exercise for the BUTT! But it also increases balance, posterior strength, and knee health. To start grab a dumbbell or bar and run it down the front of one leg hinging hips back and raising your opposite leg. Be sure to:
Hold stomach tight
Hinge hips back as you lower keeping back flat and pushing butt "to the wall" as you go down
Keep hips squared to floor
Squeeze glutes as dumbell or bar reaches the lowest position to extend back to starting position-use the butt!
Keep the stabalizing leg strong and knee soft but do not keep bending the knee as you go down keep the joint in the same position throughout the movement-it is not a single leg squat
Practice before you add weight. You may even want to begin by holing lightly on to a stable surface.