What can be said at this point about hip thrusts that hasn't already been said by Bret Contreras? We're going to use the Smith machine here and do 3 sets of 15 reps with 3 second holds at the top.
Load the bar up fairly light and really focus on getting a strong glute contraction through full hip extension. This exercise pays dividends if done lighter with a focus on mind-muscle connection. At the top of each rep, hold for 3 seconds.
Allow your toes to be off the floor so that your feet can turn outwards, aiding in external hip rotation, which is needed for a maximum glute contraction.