1. Swim with your fists. Closing your fists and swimming freestyle can really improve your stroke technique. At first it will feel clumsy and awkward, but it actually forces you to rotate your hips and move through the water the way you are supposed to. Try alternating 2 laps with fists, and 2 laps straight freestyle.
2. 6 Kicks Per Stroke Take one stroke, extend your arm, and kick six times on your side. Then stroke and extend your other arm, kicking six times on your other side. This drill forces you to stay on your side a bit longer, and gets you used to the swimming on your sides.
3. 3/4 Catchup (pronounced three quarters catchup)
Many of you have practiced the catchup drill where you touch your hands in front of you with each stroke. This one is similar, but better. Instead of actually reaching out and touching your hand, start your hip rotation as your hand slices into the water. You can even touch your ear with your thumb as your hand goes by on recovery, if that helps signal your switch from one side to the other.