Word of warning
PLEASE NEVER EVER 
use compressed air from a can or any other source to clean the sensor on a camera
Using compressed air will damage the sensor and other components in the camera.
The best way to clean the sensor is either take it to a good quality camera shop or if you really want to do it yourself buy one of the sensor cleaning kits, I recommend the dry system.
There is a small brush that you charge up with static and use it to pull of the dust. Not sure of the name but I'll find out.
Unless the sensor has heavy dust/dirt this is quite effective.
If the sensor is very dirty with stuborn dirt then the wet system will have to be used or a professional service.
BELIEVE ME been there done that £600 for repair and new sensor, thankyou very much
Gaz
