What works for me is stepping into the shot and letting the momentum of the follow through swing (straight out then up) accelerate the ball with my semi-western grip. Instead of my normal forward brush up with a full western.
Another way is, strengthen your wrist and the muscles surrounding your forearm. My friend has probably the biggest forearm I've ever seen. His left one is half the size. He plays a lot of racquetball if that helps. When we play tennis, I'm amaze how he can just rifle his forehand shot after shot with just the flick of his wrist and not much else.
Hope that helps.