1. Invest in a cleaning kit
DSLR cleaning kits can be found relatively cheap on Amazon.com, and because they are not highly technical in nature, buying an off-brand is usually acceptable. This one should suffice.
2. Clean all your gear at once
Cleaning all your bodies and lenses at once will save you time, and will ensure a freshly cleaned body is not being recontaminated when a dirty lens is attached.
3. Bodies and lenses down!
Always clean camera bodies with the lens mount facing down, and always clean your lenses with the rear glass aimed downward as well. This will prevent dust and debris from falling into the mechanism and potentially causing problems in the future.
4. NEVER touch the sensor
The sensor of your DSLR is equivalent to your own optic nerve. Don’t poke, prod, brush or otherwise come into contact with it. If there are spots on the sensor, try to remove them with an air puffer first. If they don’t come off, send your camera to a qualified service technician to have it professionally serviced in a dust-free environment. It’s worth the extra cost to ensure your camera can still see when all is said and done!
5. Use lint-free cloths to clean glass
I once read an article suggesting I use a tissue to wipe my lenses clear. I swiftly decided against this, since the amount of lint they leave behind is infuriating. Lint particles on a lens can cause shadows, spots and focusing issues, which could cost you that perfect shot. Also be sure you are using an appropriate lens cleaning solution as well.
6. Utilize lens and body caps
Even a camera housed in a bag can fall victim to dust if the lens is left attached. Zoom lenses in particular are prone to sucking in dust and debris since the act of zooming itself creates a vacuum inside the barrel. This dust can then fall into the camera body during transport. Keep both the front and rear caps on your lenses, as well as the body cap on the camera, and if you want to be extra safe, use an additional bag around each piece of equipment within the main bag. I have been shooting in dusty indoor riding arenas for years, and precautions like these can mean the difference between a camera that lasts and one that seizes up.