#2 Clean Your Lens Contacts
Dust, debris and oxidation can all interfere with your camera lens being able to communicate with your camera body. I have read many posts by photographers whose lenses just stopped working. After watching this video (which was made by photographer Tom Sapp) they reported that magically their lenses just started working again.
I think a lot of photographers may clean their sensors but skip this cleaning step. I know I did for a long time.