I open up the sides, clean all of the hardware and other stuff with a small soft brush. After that I fix all the fans with pencils and use a vacuum cleaner on low power to get rid of the dust.

I clean my Desktop carefully with air pressure and his every three month. Especially the cooling grills or rips and the fans.. Note: not to much pressure!

Those air cans are fine as long as you remove ALL dust after using it - otherwise the dust just gets blown around inside the case then quickly builds up again.

One of the important parts to clean are the fan blades. Cleaning them thoroughly with a brush and vaccuum will not only allow them to be more efficient at cooling but also quieter while doing it!

Thanks for the reminder, I usually clean my pc once a month with a soft brush. Often find a lost sock, a dead mouse and some loose change in there.

Just do t use you vacuum cleaner on any circuits! The rushing air creates static which can zap your graphics card. I tend to use an air duster, but position my running hoover nozzle near the case tovsuck up any dust in the air