Basic cleaning a digital camera is relatively easy and should be done on a regular basis.
One of the most important things to preserve the condition of the lens is not to touch it with your fingers. Before wiping off the lens, hold the camera upside down and gently blow off any grit and lose dust particles. Next lightly wipe the lens and other camera parts with a soft, dry cloth or lens cleaning paper.
Avoid putting fluid on the lens
If needed, wipe the lens with a few drops of lens cleaning fluid. It is very important to place the fluid on the lens cleaning paper or cloth, not directly onto the lens.
The best camera cleaning cloth is made of microfiber, which should be stored in a plastic baggie when not in use. Lens tissue, a swatch from a cotton t-shirt or a soft handkerchief can also be used. Paper towels, napkins and facial tissue should not be used to clean the lens.
If your camera needs extensive cleaning have it done professionally.
To clean, or not to clean, your own DSLR sensor
Digital Single Lens Reflex cameras need their sensors occasionally cleaned, though some cameras have a built-in sensor cleaning mechanism. Take a look at the video below to help you decide if want to tackle cleaning the sensor yourself. If not, use a qualified camera technician.