Don't stick it in enclosed spaces, like A/V cabinets. The PS3 cooling system walks all over the one on the 360, but it needs open space to breathe.
Keep it dust free. Vacuum the vents with a Dust Buster if dust accumulates (just vacuumed my PS3 this morning). Its best not to use compressed air on these things.
Its good to have a backup controller, though that's another $60. Be sure to properly cycle the batteries (allow it to die, fully recharge, and repeat a few times).
Buy an external hard drive so you can back up data regularly. No different from a PC, really.