I remember when doing my LTA qualifications I was working on a drill to hit the ball consistently deep. We had to put a down line half way between the baseline and the service line. Since then I have worked on a silmilar drill but this time focusing more on shot quality rather than just depth: I call it "the Teardrop drill" because if you hit the ball in this area your opponent should finish the point leaving you crying. 

How does the Teardrop drill work?

1. Using down lines, draw a "Teardrop" on the other side of the net.
2. Rally with a partner avoiding to hit any ball in the "Teardrop".
3. As it is a demanding drill on your partner, rally for sets of 2 minutes only. At the end of each set record how many balls you have hit in the Teardrop (the least the best).

You cannot dictate the game if you keep on hitting shots that resemble a “not to lose type of tennis”.

While I started using this drill for aggresive players I realised that the teardrop drill is a great drill for all styles of players. For players who strike first and look to move forward and end points at the net or by forcing the opponent into error, hitting the first 2 shots hard and aggressive outside the teardrop after your serve or return should elicit an opportunity ball. If you are a counter-puncher or all-court player who works the points more, you may need to hit 4 or more consecutive shots outside the triangle before you earn an opportunity ball. This can vary for all players depending on variables such as the opponent, the pace, and depth of your shots, the environment and surface, the quality of your play on a particular day and how well you are serving and returning on a particular day. On the other hand, if you hit inside the teardrop, you can expect to be dictated.

The size of the triangle depends on the ability of the player. I usually start with the back of the teardrop placed four racquet lengths inside the baseline and three racquet lengths inside the sidelines. It is time to move to a bigger target when you are hitting outside the triangle 60-80% of the time.

A great drill that simulates a point is a two-on-one drill with the teardrop marked on the two side. The coach feeding is on the two side behind the baseline and feeds a ball to the player on the one side. The player on the one side is aiming to hit his first two shots outside the teardrop and the players on the two side can hit anywhere. If the player on the one side hits inside the triangle, the players on the two side attack his/her shot to any part of the court and they must come to the net, and the point is played out. If the player on the one side hits consecutive shots outside the triangle and has earned themselves an opportunity ball, they must come to the net and play the point out against the players on the two side.