I follow Thom Hogan's advice - it's for Nikon but works equally well for Canon, and about once a year or after a really dusty trip I get it done professionally.On a side note, do you clean your own sensor on your camera? I've tried several methods but can never get it fully cleaned. I took it to a place in OP about a year ago after Arches NP and they did a great job but I'm starting to see several dust spots again.
http://www.dslrbodies.com/cameras/camera-articles/image-sensors/cleaning-your-sensor.html