Instruction - Learning The Dink
It is easiest to hit a dink from very close to the net, so that is where you should first begin practicing the dink. Practice hitting the dink straight ahead and then practice hitting it from forehand corner to forehand corner and finally backhand corner to backhand corner. You should try to make all balls bounce in front of the no-volley line and they should be short and low enough that the player your practicing with couldn't kill the ball if he/she wanted to do so. While you will probably have to step into the no-volley zone to hit a lot of the dinks, you should immediately step back behind the no-volley zone line before the opposing player hits the ball. Otherwise, in a game they will hit the ball at you and you are not allowed to hit it unless you are behind the no-volley zone line.
To help you concentrate and have some fun while learning the dink, you can play a game with four players where everyone has to dink and you lose the point if the ball lands behind the no-volley zone line. You can still play to 11 points, but you have to start the point nicely to each other for this game to work.
When you are more proficient, you can advance to the next game which is more like a real game. In this game, 4 players start off dinking to each other but looking for the opportunity to kill the ball if the opponents hits the ball to high. If you are doing this drill with players of mixed abilities, the better or stronger players should be careful not to hit to hard at the weaker players. Remember this is for fun! We don't want anyone hurt!
Once you have learned to do the short dink and survive in the dink battle that usually ensues, you are ready to learn to dink from further back. To practice this with 4 players, have 2 players stand at the no-volley zone line and the other two players stand at about 3/4 court position on their side of the net. The two players at 3/4 court try to hit soft dinks while the two players at the net position try to hit the ball back nicely so they can try another dink. After a little while, reverse positions and practice for an equal amount of time. This might take quite a few practice sessions or one, but eventually you will get the feel of how hard to hit to make a good dink.
When you can do the 3/4 dink in practice, then you need to try hard to incorporate it into your practice games. At first you will miss more than you did in practice, but if you continue trying it in game situations, then eventually it will work. Every time your team serves and they return the ball, you should be hoping for a 3/4 court return or shorter that is not too hard to try your dink on. And don't forget to move into net behind it!
This does not mean you should try a dink with a backhand in a game when you can only do it with the forehand in practice. Try everything in practice before trying it in a real game.
Only after having a reasonable amount of success with the dink from 3/4 court and closer, should you begin to practice the dink from behind the baseline. Also remember that if you have bad legs and can't get to net easily, you probably shouldn't dink from the baseline even if you can do it well, because they will just dink it back short and you won't be able to get there.