If you have an interchangeable lends SLR type digital camera, then it’s essential that you clean the sensor on a regular basis. Blasting air on the sensor is not enough since much of the dust and dirt will stick to the sensor.

You can help reduce the amount of gunk that collects on your
camera’s sensor by turning your camera off before you switch lenses.
When you camera is on, the sensor has a slight static charge which can
attract dust and grime. The only time you’re safe is if you never
change lenses.

I clean my sensor before each major trip that I take. Or, if I’ll be
home for a while, then I’ll clean it before an important shoot.

There is a simple test you can perform to determine how much dirt has
collected on your camera’s sensor: Set your camera to Aperture Priority
mode, use a setting in the range of f16-22, in manual focus mode, set
the focus to infinity (the farthest distance available) and then take a
photo of a clean white surface. After opening the image in Photoshop,
choose Image>Adjustments>Levels and pull in the upper left and
right sliders until they touch the ends of the bar chart that appears
(you might have to bring them in further than that on some cameras). If
you see any specks in the image, those are most likely caused by dust
and dirt on the sensor.

To find out the best way to clean your sensor, visit www.cleaningdigitalcameras.com