Stop trying to hit up on the ball. Topped shots and fat shots are caused by the same thing, hitting up. Hopefully your woods have enough loft to get the ball airborne without you needing to help it. Todays woods are available in less lofts and golfers are buying these less lofted woods thinking they're going to hit the ball further. When they look down at address they see little loft on the clubface and then swing up trying to add loft leading to what causes topped shots. Fact is recent test have shown most amateurs will get better distance using higher lofted woods, 11-12 degrees in the case of a driver.
One way to stop topped shots (and fat shots) is to image a park bench about 5 feet in front of your ball. Try to hit the ball under the bench. You'll come into impact with your hands leading and the shaft leaning forward, two vital elements of proper impact geometry.
David Laville, G.S.E.M.
The Golfing Machine Authorized Instructor