Having the right stroke for your shots can mean a big difference between a good game and a great one. I've been working on my forehand for the last three sessions and I can really feel the difference when I consciously carry out a proper forehand.
The key is pronation, coming in with your shoulder and leading with the elbow before the wrist comes in to do the trick.
For each shot, you'll want to minimize the swing of the whole arm, and instead concentrate on having each of the three joints being used in quick succession to add more power and control to the shot.
And instead of talking my face blue to explain the intricate coordination of our arms, I found a video online that does the trick.
It features current World #1 Tai Tsu Ying in a short training session. Notice her first shot and her last, and you'll see how it's supposed to be done.