Hitting straight, in the centre of the mallet head.
1. You can practice with a tennis ball on your carpet or other flat indoor surface. Aim to get the ball to hit a chair leg gently from about four feet.
2. You can also hit a tennis ball to a skirting board. If you are hitting it with the centre of the mallet at 90 degrees to the skirting then it will come back to you exactly. This is a good exercise. Remember to keep your eyes on the ball and don't look up. The ball will come back- if you are hitting correctly it will come back to you so you don't need to watch it hit the skirting.
3. Try exercise 2 at different distances from the skirting and hit it at just the right strength so it returns to your feet at a 'catchable' speed.