Bath or shower before going to bed. Do not eat on the bed or on soft furnishings where house dust mites abound. Do not keep animals in bedrooms. 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.