In general, the answer is "No", there isn't a lot you can do about rust. That's because the most serious rust problems come from water trapped inside body folds, doors and such and you won't even see the rust until the body has rusted through starting from the inside. If you keep your vehicles a very long time and aren't too fussy about the paint job, you can try going over them once a year and wire brushing any visible rust then treating the area with Rust Reformer, Naval Jelly, or similar stuff. You can then paint the treated rust and any nicks in the paint job with a spray can of the proper touch up paint from the parts store. That actually works OK with some white paint jobs. Areas under the car can simply be sprayed with flat or semi-gloss Rustoleum black paint after treatment. The surface treatment may help with things like pick up beds and oil pans. It won't do a thing to keep your doors from rusting out due to moisture trapped on the inside.