Triceps, Trapezius, Shoulders, Glutes, Chest, Core, Back
Set up from a kneeling position, feet together, hands about shoulder width apart. Engage your core by assuming a Posterior Pelvic Tilt (Tuck your tailbone, eliminate any arch in your back). Squeeze your glutes and raise your knees, there should be a straight line from your head to your heels.
Generate total body tension, gripping the floor, squeezing your armpit, glutes and core engaged.
Now begin bending your elbows, and keeping them tucked in to your sides. Lower your chest to the floor, maintaining tension throughout the movement. Pause at the bottom, and then push up, exhaling on the way. Think about screwing your hands outward, and driving through the floor.
Once you are on top position, rotate your body clock wise by crossing one of your arms over the other and finally moving other arm the same way so you are now again in a standard push up position but pointing in another direction.
Repeat for Repetitions.
Avoid flaring your elbows. Don't allow your hips to sag, or back to arch at any point, your whole body should be engaged throughout.