Basic rules for serving

• The ball must rest freely on the open palm of the stationary hand
• The ball must be above table height and behind the end line at all times
  
• The ball is throw up vertically at least 16cm
  
• Strike the ball as it drops, to land first on your side of the table, then the receiver's side

These rules give you lots of scope to experiment. A good server varies the spin, speed and direction of the ball, and all players should be able to hit a short, slow backspin serve or a fast, long topspin serve, using either forehand or backhand.  All serves should be low over the net, otherwise your opponent can easily attack them. 

Backspin serve
Here you hit the underside of the ball, using a brushing motion.  The bat face should be completely open - start and finish the service action with the bat horizontal to the table. The bat must accelerate towards the ball as fast as possible to maximize the spin. Acceleration can come from the elbow or elbow and wrist together (better but more difficult). To shorten the serve, a finer contact underneath ball is required and the bounce on your own side should be closer to the net. 

Topspin serve
Hit the ball when it is close to table height, using a closed bat angle.  Brush near the top of the ball using an upward and forward motion, aiming to bounce the ball on your side of the table close to the end-line.