Position yourself on the baseline, in profile to the net, with one foot slightly in front of the other for better stability.
Use an appropriate grip for your serving style. For me, I use the hammer grip, which gives me more power and room for improvement.
Hold the racket behind your back with your free arm. Bend your knees and hips slightly to prepare for the push-up.
Toss the ball into the air in front of you, slightly forward and toward the side where you will hit the ball.
When hitting the ball, turn your body sideways toward the net using rotation of the shoulders, hips, and legs to generate power.
Fully extend your dominant arm up and forward at impact with the ball.
The racket should go over your head to maximize power.
Aim to hit the ball at the highest point possible, just past the top of the bounce. This will allow you to hit the ball with a downward trajectory, increasing the speed of your serve.
After hitting the ball, continue your movement by following through completely with your arm and body. This will help you transfer all your energy into striking.

Exercice de service avoir un service puissant et efficace

255 Tennis exercises and tactics - The V game

256 Tennis drills and tactics – Use your strengths