The push-up begins by walking yourself back into a plank with your arms straight, palms under your shoulders. Push your knees straight as you squeeze your butt and abs. Make your body as rigid as possible from your knees to your neck. Wrists, elbows and shoulders should be stacked over each other before beginning the descent. Strongly rotate your palms outward and begin to drop. Remember to keep the elbows from flaring out by keeping the elbow stacked over the wrist as vertical as possible. Once your reach the bottom drive up strongly as you can without losing the tension in your butt or abs.
If using the rings make sure to take the time to situate them about shoulder width apart.