[Christ]

You want to envision a straight line back on both sides from your widest point on the front of your bike. You don't want anything sticking out past that point, and you want that point as thin as possible. Height isn't SO much of a concern on bikes, but it's still a way to reduce frontal area. If your fairing/windshield has things sticking out on it more than about 1/4", see if they can be removed/smoothed in.

Anyway, when you get your lines done, imagine them tapering in at a steady 10-12* from the widest point on the front of the bike, and try to keep the airflow straight as possible at that line.

If you need a pic, lemme know. While you're at it, Check out Vetter's site: Craig Vetter, designer and inventor of the Windjammer fairing,Triumph Hurricane Motorcycle and fuel economy motorcycles

Pay specific attention to his fairings and aerodynamics, but don't mind the freaky scooter he's driving now. He's a little eccentric by some measures, but I believe he's out for the best he can do. He's a very good study, though. You'll likely learn alot from him.