Great game. I played a lot and for local league teams until my knee gave out (bummer). As others have said get a couple of lessons to learn the basics in order to get off on the correct foot/feet (forgive the pun).
Tips... squash is unlike other racquet sports. In Tennis, Table Tennis and Badminton 9 times out of ten if you can get the ball past your opponent you've won the rally. In Squash, if you get the ball past your opponent it will usually come off the back wall and they'll return it. To win a point you'll have to manoeuvre your opponent out of position. This can be difficult because the court is quite small. Therefore, being aware of where your opponent is standing is critical. There's no point in hitting a blistering drive an inch above the tin if you're opponent is in position and waiting for the ball! So, before you play a shot, think about where your opponent is standing and try and place it as far away in the court as possible from where your opponent is standing. Try and make them work, or move to retrieve the ball and try and avoid hitting it back to them...