The Hip Circuit, which I also call the Fire Hydrant Sequence, is a wonderful series of exercises for improving hip strength and range of motion.  They should be performed from a hands and knees position with elbows straight and ankles dorsiflexed.  Each motion should be done at a controlled pace and at your maximum range of motion.  Each exercise should be performed 8 to 10 times per side before moving on to the next.

Fire Hydrants

Lift your knee out to the side using your hip.

Forward Circles

Rotating from the hip, make as large a circle as you are able to using your knee.  Lift your knee to your chest, then out to the shoulder, then up and behind you, and finally back to your chest.

Backward Circles

Rotating from the hip, make as large a circle as you are able to using your knee in the reverse direction of the prior exercise.  Lift your knee up behind you, then out to the shoulder, and finally back to your chest.

Rear Leg Lifts

Extend one leg behind you with your knee straight.  Lift up and down to your maximum range of motion from your hip.

Lateral Leg Lifts

Extend one leg out to the side with your knee straight with your foot in line with your hands.  Lift up and down to your maximum range of motion from your hip.

Hack Saws

Lift one leg so the shin is parallel to ground.  Move your knee up towards your shoulder and then behind you.  The motion should go such that your shin remains parallel to the ground.