From analyzing the top pros, I came to the following conclusions about why their drive serves were consistently more powerful and sounder than the amateur players:
 

• They do hit the ball on its descending path.
   
• They do use an angled ball toss for greater consistency, power and deception.
   
• They do use a diagonal two steps motion. Same advantages as #2.
   
• They synchronize and utilize a high elbow racquet setup. The high elbow technique is where a player’s points his/her elbow to the ceiling, elbow is bent, racquet points at the ball, and then the racquet is accelerated to the contact point with the elbow leading the stroke, thus, facilitating an excellent wrist snap into the ball.
   
• They adhere to fundamentals, like staying low and level, using a two steps approach, synchronization of the lower body before the upper body, culminating in the powerful wrist snap, hitting the ball flat and level, eyes focus on the ball, and the service motion is the same for every serve, the only different is the ball drop zone.