the obvious things can be the ones that turn around and bite you in the rear end when ignored. our '78 left us stranded on the side of the road 42 miles from home last october because i did not check the "idiot" light for the charging system.
i weekly check the floor of the garage for new or unusual puddles of fluid.
your small airplane mechanic's guide will tell you to replace all rubber parts every five years.
other than the guibo and the timing belt, everything else is just about standard automobile maintenance.