Reduce dust mites from their reservoirs, using dust mite covers. These are a very efficient way of keeping the dust mite inside mattresses and stopping the food supply from entering into mite colonies. Plastic sheets are good only when they are brand new. Fixed carpets, especially those with thick underlay, provide excellent protection for the dust mites. Even the strongest vacuum cleaners cannot produce enough draft in the depth of the carpet piles to dislodge them.
Rugs are the best way to go.
Vacuum cleaners are efficient in removing easily dislodged particles. Be sure to have a fine enough exhaust filter though, otherwise particles will just be redistributed throughout the room. Insecticide sprays turn out to be efficient only very temporarily and all of the marketed products also affect other insects that are predators or competitors of the ubiquitous mite. Thus, as the mite eggs survive and hatch, there is no longer adequate competition to hold their numbers down and the population may even expand. Scratch testing on the skin using well-defined allergen extracts remains the best way to test for house dust mite allergy.