The correct way to do a pushup is by keeping the hands directly under the shoulders, and not flaring the elbows out, as is common. Doing this will prevent shoulder impingement, which causes shoulder pain, according to Sabrena Merrill, a personal trainer and CrossFit coach.
Positioning the body is key to performing a proper pushup.
Step 1: Assume the plank position
Use the palms and toes to balance the body.
Step 2: Brace the core
Squeeze the glutes, brace the abdominals and keep the feet together.
Step 3: Perform a rep
Slowly lower the body, being sure not to let the hips sag at any time and keeping the elbows close to the body at all times. Pause when the body's about to touch the floor, and then return to the original position.