Get a better tripod. I have a Manfrotto 190XProb with a bubble level on it, I make sure that the feet are perfectly level first and then there is a bubble leve on my tripod head, which I then make sure is perfectly level. Then I mount the camera with a bubble level in the hotshoe to make sure that it's completely level. And I just test it by panning the camera. If the bubbles move I just start over at making sure everything is level.