If the ball is high and quite close to the net, go ahead and hit it flat. If the ball is quite low, hit with topspin. To hit a good put-away you have to remember to:
1.Keep your head cool while hitting and see the ball.
2.You have to get to the ball early;It's harder to hit it on the run. If your opponent regularly hits short return off your serves, you can anticipate it by moving a little more forward right after you've served your bomb and get ready to dash forward.
3.Do not try to hit it too hard! The more skilled a player gets, the more consistent he gets with shots with a lot of pace. A put-away needs to be hit with high %, so take off a little pace to make sure it lands in. You have to experiment on how hard you can hit it to consistently keep it in the court. "But won't the opponent get to the ball if I don't hit it with enough pace?" " Not if you place it well with enough depth." The placement is a very important factor in put-aways! Even if you didn't hit a clean winner with your well-placed put-away, it's not likely that it's coming back or if it is, the ball will be short and you can hit another put-away.