dust filters on INTAKE fans make a world of difference. If your case doesnt have these built in, then you need to screw them onto the fans... and clean them every few months. not exactly hard, just a pain.
some sort of vacuum attachment to suck out loose dust is fine.
canned air is fine, but when blowing out fans, hold the fan blade with your finger to prevent them from spinning. you can damage the bearings inside if the air spins them faster than they're meant to spin.