Read the Opponent’s Spin
All high-balls should not be smashed in the same manner.  When you see a high topspin ball, step back slightly, start your racket high, and smash forward and down.  When you see a high backspin ball, step forward, start your racket lower and the angle more open, while smashing forward and slightly up.
 
Add Spin to Your Smash
A smash with some topspin will possibly be 10% slower, but it will usually have about 50% more control.  Be consistent in smashing – add topspin!
 
Place Your Smash Correctly

 
 
 
 
Most players agree that if you win a spectacular rally or win an easy point, it just counts as one point. BUT actually, they don’t…
 
Let me give you a scenario.  You are winning 9-7 in the final game.  You serve short topspin and your opponent reads your serve as backspin.  He steps forward and pushes your short topspin serve giving you an incredibly easy popup.  At point-blank range, it would have been nearly impossible for him to return your powerful weapon, BUT unfortunately for you…   you miss your smash!