Try monthly tick/flea spray prevention or weekly anti-tick/flea shampoo. There are also various other ways; we recommend that you bring your pet to the vet for preventive treatment.
Of course, you could avoid fleas altogether by making sure the environment your pet lives in is flea-free. Flea sprays for furniture and gardens are very effective. Try to prevent your pet from wandering while not under supervision - they can pick up fleas from all sorts of places outside your home which you have no control over - and they could also get into trouble or get injured.