Housekeeping!

I’m wondering what the best way to keep the guts of my PC clean. Everyone in my apartment smokes like a factory, and to counter this I’ve put hepa filters (custom cut!) in the air intakes. Are there any better filters out there? I’ve noticed that there’s a little dust in there too, not sure how…
Also, I know that static is murder to your computer, so what’s a good static free way to clean the inside? I’ve got duster, but that only goes so far.