Maintaining the batteries (especially when not using them for long periods of time) is one of the most important things you can do. Check out this post for more information.
I use the following
1) For the body/propeller and lens/sensors use a microfiber cloth made wet by spraying non-alcoholic lens cleaner
2) For the dirt areas especially next to gimbal and the intake fan vents, I use a rubber based hand air blower and fiber brush from amazon https://www.amazon.com/Altura-Photo...8&qid=1525693689&sr=8-7&keywords=lens+cleaner