LUBE all the little forgot-about things, such as hood latches/hinges, P-brake cables, throttle-cable, throttle-linkages and pivot-balls, door latches/locks/hinges, jack, jack and wrench stowage bolt-threads, etc., etc.
Do this at least twice a year.
Just before winter, clean the block-heater-cord plug-prongs and lube both the prongs and their protecting sheath with Vaseline, replenishing the vaseline after any heavy rain or snow; you will appreciate this little attention to detail after a big freezing rain.
CLEAN the rear axle vent and it's hose.
Flush and replace the brake-fluid bi-annually.