Use entrance mats. One in front of each outside door and keep them cleaned off. Outside mats can be hosed off to clean. You can also prevent dust build up by having inside mats for doorways. Keep them vacuumed off or take them outside and give them a good shaking.
Change filters every 1 to 3 months. It will not only keep dust from building up but will also keep your air conditioner in better condition.
Brush your pets regularly. Dogs and cats carry a lot of dust around and loose hair that will get all over everything.
Keep windows closed and check weather stripping to see if it needs to be replaced. Dust flies in from the outside when wind blows.