Like everything we own, cameras and lenses get dirty and should be cleaned from time to time. It’s really not too difficult but make sure to do it right. The feeling of scratching an expensive lens while trying to clean it is something you’ll regret for a while.
First, you should take a brush that's designed to clean photography equipment and brush off all surfaces.
Now, take the Air Blower and blow any remaining loose debris (i.e. sand, dust, etc…) off the camera and lens surfaces. Pay special attention to crevices. You should also make sure to blow out the memory card slots and accessory ports.
Next, get your Cleaning Cloth/Cleaning Tissues wet with some of your Lens Cleaning Liquid, and clean all surfaces. When cleaning glass surfaces, like lenses and LCD screens, make sure to move the cloth/tissue in a circular motion. I personally like a Microfiber Cleaning Cloth over tissues.
I would not try to clean the rear lens element of a DSLR or Compact System Camera (CSC) beyond just blowing any dust off of it. Being that the rear lens element should almost always be protected from the elements, it shouldn't need to be cleaned much.
Do not use compressed “air” on a camera. Unless held perfectly upright for short amounts of time, these can emit aerosol, and the pressure involved can damage some areas of a camera.
There are techniques to clean a camera’s sensor, but other than blowing off the sensor with a blower, I would recommend not doing this yourself. Although you can, it would be terrible to damage your camera’s sensor. If your camera’s sensor gets dirty, have it professionally cleaned. A professional knows what they are doing, and if they happen to make a mistake, they should cover it.