Lie on side. Stack top foot over bottom foot. Dorsiflex (bring toes to knee) and slightly pigeon toe top foot (this is the position to keep your foot in for the raises).
Squeeze medial glute (side of hip) to raise leg as high as you can. Lower leg back down in a controlled manner. Repeat.
Perform 1-5 sets of 8-12 reps per leg. Or, perform 1-5 sets of 20-40 second intervals (doing as many reps as possible during those intervals).