When training for the sport of squash it is important to incorporate a lot of different running and agility drills as this is going to be of paramount importance when it comes to achieving a successful performance.
The first type of drill you should practice to improve your squash game is a simple 20 meter shuttle run. Set up pylons at the 5 meter, 10 meter, 15 meter and 20 meter marks and then run to the 5 meter one, turn and come back to the start and the make your way to the next one and so on until you have completed up to the 20 meter pylon mark.
The next type of exercise that will enable you to improve at squash is working on your lateral jumping ability. Some times you are going to have to rebound off the floor in order to hit the ball and having the strength and power to do this will be essential. To practice this, stand about 3-4 feet away from a wall. Then take one or two steps towards the wall, stand with both feet together, bending at the knees, and bound off the floor as high as possible. Reach your arms upwards and touch the wall at the top of the jump. Repeat this process 5-10 more times per session. Eventually you should notice that you are able to reach farther up the wall hence your vertical jump will be improving.
The final exercise you should perform works on your lateral jump ability as sometimes it will again be necessary for you to move in the sideways direction very quickly in order to interact with the ball. Start by placing two long skipping ropes about a foot away from each other lengthwise down the room. Next stand at the start of the ropes on the outside of one of them. Then you are going to jump sideways towards the other rope and land on the outside of it and then back again to the outside of the other rope. As you are jumping you will slowly move in the forwards direction until you have reached the end of the ropes. It is going to help you most to try and stay in the bent knee position to both absorb the shock from landing and then also allow you to move more rapidly through this exercise.
Performing those three exercises should get you well on your way to improving your skills for the game.