The only things I do are:
- dusting off;
- wiping the external body parts with a cloth;
- wiping the optical surfaces of lenses with a lens pen;
- taking all precautions mentioned by MFloyd, four posts above. I also wipe or protect the camera / lens junction when it rains, given that most lenses I use have no gasket (the Tamron 45/1.8 being one of the few exceptions).
For sensor cleaning, I always visit a serious shop owner who would do it for free 50% of the time (depending on our other business). And I only ask for it when there is an apparent problem on a NEF, rather than "preventatively", which would increase the risk of accidental scratches.
So far these precautions were ok; I never had to return a camera for repair, and especially not the Nikons (D700, D800, Df). The only trouble was having oil sprayed onto the sensors due to the mirrors: neraly nothing with D700, a bit more with D800, and even more with Df that initially needed its sensor to be cleaned every month. But now, that lousy running-in period is over. Last cleaning was 6 months ago I guess.