Only drive it when the roads are clean.
Seriously, wax will help with rain spots, paint fading, bird poo, and the occaisional squashed bug, but no paste is going to protect against rock chips. The 3M clear bras are decent for preventing front end rock chips, but they only protect so far. Short of an SUV rock guard, mud flaps, or moster truck wheels, I don't think you can do much to prevent rock chips.
How you drive has a big effect. Always leave at least 3 car lengths between you and the car in front of you. Don't spend a lot of time in the far right or left lane, where shoulder dirt gets pulled up more often. Never follow semis, dump trucks, especially open back hoppers. And avoid dirt roads.
I may not be the best person to give advice on this subject, though, since I plan to drive mine like I stole it.