Keep under 2500 rpm, keep your fluids up, and make sure your fuel doesn't sit too long. Thats my course of action with mine.
These engines are capable of long lives with just the basic maintenance stuff.
Mine is crusty and old with a quarter million miles on it and it starts up with no fuss, no smoke, and gets pretty decent mpg's.
I'm going to change the oil next summer and do all the filters.