Can of air or vac. Turn PC off. I found it easier to completely remove the heatsink (freezer 64 pro) to suck dust out. Remove fan too, as air blowing / sucking can cause it to rotate faster than it's supposed to and maybe break it (or start making a noise).
My next case (likely P182) will have just 1 case fan at the front + filter to control dust.
My next case (likely P182) will have just 1 case fan at the front + filter to control dust.