My darkroom is in the basement. I hardly ever clean anything, like Thomas indicates. I keep negs in Printfile pages, but in books. I am very attentive to using Dust Off on each neg, both sides, after placement in the carrier, just before insertion into the enlarger. The humidity in the basement is 45% - 55%, sometimes a bit lower in the winter.
If I make 10 - 12 16x16 prints from 120 negs (usually 2 of each), when I go to spot, after toning, etc. I may have an average of 2 spots per print.
What I think helps for me: Very little cotton in the darkroom (just what I am wearing and a towel), an Aristo cold light head (I used to use a condenser, and noticed the drop in dust immediately when going to the Aristo (1982), and there is no traffic in the darkroom unless I'm working. I also have a drying cabinet I built attached to the wall, right next to the sink, and negs are hung there right after Photo Flo.