The No. 1 rule in avoiding traffic tickets is to not get noticed, and nothing draws attention like a Bondo beater dragging itself down the highway. Keep your car in good working order. Bumper stickers, excessive window tint, iffy car modifications and certain kinds of vanity plates also attract unwanted attention.
If you have a taillight out and parts are falling off your vehicle, you're effectively demanding that an officer pull you over. By definition, broken lights and faulty signals mean you cannot drive safely or legally, and if an officer has to flag you down as a safety hazard, then he or she is much more likely to ticket you for any other mischief you've been up to, like speeding.
In any case, getting a tune-up before embarking on a road trip is always a sensible precaution, one that can save you lost hours, even days, awaiting a tow or repair. While you're at it, why not have your speedometer calibrated? It's guaranteed the one in the highway patrol car will be.