Don't drop or knock the lens. Take care not to put a lot of pressure on the lens. I guess this means it may crack under pressure of the decisive moment.
Don't get pesticides on it. Don't carry the unit when it is still attached to the camera body. Don't store it on a beach or in direct sunlight or in high temps or humidity or where there is high concentrations of sand, dust or dirt, or fire, or near heaters, air conditioners or humidifiers, or where water may make the unit wet, where there is vibration, or inside a vehicle. Don't disassemble.
I'm glad I read that, otherwise I never would have known.