Rennae Stubbs had a long, healthy career because she had great technique, especially on her serve. She didn’t try to muscle the ball. She had a good stance, very relaxed shoulders and legs, and a lot of wrist snap. Her motion was simple and smooth. That’s why club players should emulate it. There’s no need to adopt an abbreviated service motion or an extreme stance or grip; let the racquet do the work for you.
On the second serve, no one was better than Pete Sampras. While you couldn’t possibly replicate the accuracy and high kick of his second serve, there’s something important to learn from it: You can’t be afraid to hit second serves. You must have a reliable second serve to bail you out.