If you have been training in the pool you might resist my suggestion to swim with a high elbow. I am not suggesting you abandon your pool technique altogether when you swim in the open water. However if you shorten your stroke you also shorten the distance your arm must travel before your hand re-enters the water (at the half-way mark) and you begin to elongate your arm, and begin your pull. In adopting this technique your body will automatically align itself for the perfect roll, which is more effective for a clean breath too. To check your stroke as you raise your arm in the water look directly at your elbow. Your head will be perfectly aligned with your body. Make sure your hand re-enters the water at a 30 to 45 degree angle, four to eight inches under the surface of the water. Lift your elbow out of the water as if on a puppet string, at a 90 degree angle. After your initial "pull" be certain to brush thumb past thigh before recovery to get the most from your stroke.
~Coach Pedro Ordenes, waterworldswim.com