The support pages for the Mac mini may be of help:
As to keeping it running smoothly, there's not a lot you usually need to do. The most important thing is to make sure that any applications or peripherals you are interested in are properly compatible with OS X 10.8. Incompatible apps and drivers are the most common source of problems and frustrations.
Then give the mini a good environment: static-free and with good power. At least give it a good surge protector, and by that I do not mean the $9.95 hardware-store specials which often cause more harm than good. A power conditioner or UPS would be better if you're prone to having power glitches.