Assume a pushup position, hands wider than shoulder width apart, feet together.
Descend to one side by bending the working arm, keeping the elbow tucked in.
Try to keep the other arm straight, and minimise it's involvement.
Resist rotation through the torso by staying tight, squeeze the glutes, maintain a Hollow position & Posterior Pelvic Tilt throughout. (Keep the tailbone tucked, core braced, don't let the hips sag)
To reduce stress on the wrist, as you descend outwardly rotate the hand of your extended arm.