I have played tennis for about 10 years, and am a beginner at squash. What are the key differences between hitting a forehand squash shot and a forehand tennis shot, that I should be aware of as I practice playing squash?
Unfortunately, I've played too little tennis to give you an expert answer, but I'll give it a go anyway.
The two main differences that I can think of are these:
(1) The distance to the ball In squash, you generally want to stand closer to the ball when hitting it, to give maximum strength to your swing. In tennis, you need to be able to spin/curl the ball as well, which means that you'll have to stand a little bit further away from the ball.
(2) The height of the ball when hitting it. Obviously, this is quite closely related to the first point, but it's still worth pointing out as it's a common error made by beginners. In tennis, you want to hit the ball when it's higher up, in order to be able to play the ball harder. In squash, the problem of getting the ball to dive after passing the net is non-existent, whereas the player can focus more on pure power in the swing.
Basically, what you want to do in squash is to hit the ball close to your feet, with your entire upper body above the ball. This will allow you to use your entire body in the swing, making it more powerful than a swing with merely your arms. It's hard to explain, but try it out on the court and it should make sense :)