First the dog must be treated with some type of time released protection. One of the most commonly known is Advantage because it was previously only available through veterinarians. However, their are many other products available through pet stores that do the job just as well if not better. I have always used Bio Spot. Not only does it kill adult fleas, it kills eggs and larvae as well and it repels mosquitoes.
Advantage is an adulticide which means that it only kills the adults.
If you use advantage your veterinarian will recommend using Program as well which has also just been released over the counter. Program is a once a month pill that will effect the female flea causing her to lay non-viable eggs. It does not kill adults or effect the male flea. So, your dog will still get bit by fleas. There are several other spot on products available through pet stores.