Living in south Florida the humidity helps but also my darkroom has tile floors, an exhaust fan, a filter over the ac vent and I cover the enlarger with a large garbage bag when not using it. If I notice dust on dry negatives I use Dust-Off. Negatives are kept in Print File sleeves and the sleeves in negative envelopes and those in negative storage boxes. There are also anti-static brushes and cloths available. Be sure to clean up any chemistry especially fixer drops because once they dry they will be a source of dust.