i do the minor shit...i'll vacuum and get the little wipes for the leather and the dashboard/console area. and then usually run it through a $7-8 touchless carwash every once in awhile. i never wash the outside myself because i don't really have a place to do it in my building, not to mention it's a pain in the dick.
if it really looks like i need a detail, i'll go get the bumper to bumper. i do this maybe like once a year or so, maybe a little longer than that depending on how much minor upkeep i do