A good start is to restrict which rooms your pet is allowed in to. Living rooms and bedrooms which have a lot of fabrics and carpets will easily collect pet dander.
Use a damp cloth to dust hard surfaces and floors regularly to reduce build up of dust and dander.
You can never remove all pet hair and dander. Even the most efficient vacuum cleaner can’t remove all dander. It remains for weeks or sometimes months and can still cause symptoms despite regular cleaning, even after the pet has been removed.