If I had only one tip to give it would be commitment. Without it everything else will fall apart. I think as a whole we all know what we have to do and there really aren't any secret tricks. Its sticking with your plan that is the hurdle.
Consistent commitment to an efficient circuit training program that incorporates both an aerobic element and strength conditioning. Oh yea, Eliminate anything containing High Fructose Corn Syrup from your diet.