While we're on the topic of general cleaning...
All my new lenses get a UV filter first thing after they come out of the box. A UV filter has very little effect on the image itself, and this is a good thing. It basically acts as a $60 insurance policy on the front of a $1200 lens. Anything that might scratch or damage the lens will be stopped by the UV filter, which is easily replaceable and won't ruin a day of shooting.
You can also minimize the intrusion of dust by minimizing lens swaps, especially during windy moments outdoors. I keep Canon's 24-105L lens on my 5D, and that covers the majority of what I need. Sometimes I have to swap lenses, but more often than not if it's going to be an outdoor shoot I'll keep a longer lenses mounted on one of my backup bodies.
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