I don't know about the rest of the country, but where I am from fleas are bad this year. I mean BAD. If you live in an area where fleas(or ticks, if thats the case) can be a major problem, do yourself a favor and be pro-active. Trust me, it is a whole lot easier to try to prevent an infestation than it is to get rid of one. Now that being said, there are a ton of options out there. The problem is that the products on the market all work, but it all varies between situations. For me personally it has been Advantage.
Advantage is a once monthly spot on treatment. It kills fleas, flea larvae, and lice. IT DOES NOT DO TICKS. I personally do not have a problem with ticks, and thus I use this. Now the company that makes Advatage also makes Advantix which controls fleas, flea larvae, ticks, lice, and mosquitos. The thing to keep in mind is that in order to add the extra ingredient to kill ticks, they have to use less of the ingredient that kills fleas.
Frontline is another option. This is also a monthly spot on treatment, and both the regular and the Plus kill fleas and ticks. The Plus also kills flea eggs. I personally have not had a whole lot of luck with Frontline or Frontline Plus, but I know a lot of people that swear by it.
There are also a couple options that are available through your vet. Keep in mind that these are perscrition only and often cost more.
Revolution. This is monthly spot on treatment for fleas. In addition to being a flea treatment, it also protects against heartworms, ear mites, and ticks. I do not personally know much about this product, but it does seem to to have good reviews.
Comfortis. This is a relatively new product. It is a monthly pill that you give your dog which protects against fleas. I have heard nothing but good things about this pill. If you are someone who is really having trouble getting rid of fleas, then this may be the answer for you. Consult with you vet to find out. I would say the only bad thing, is that since it is a pill, it can sometimes be hard on your pets stomach.
Last but not least is a home remidy. Garlic. There are no studies that have proven its effectiveness, but none the less, it is said to help prevent against fleas. Rememeber hat although safe in small amounts, garlic can be toxic to dogs in large doses. If this is something that you decide to add to you dogs food, don't get carried away.
Dr. Messonnier (author of The Natural Vet's Guide to Preventing and Treating Cancer in Dogs) recommends one clove of fresh garlic per 10 to 30 pounds of weight a day, three to four days a week, to boost the immune system and cancer prevention. You could also try garlic powder. Give 1 tsp per 20 lbs a day, three to four days a week. I personally try for about every other day.
Please understand that if your pet currently has fleas(or ticks) then these products probably will not have your desired results. You will need to take extra steps to rid your dog, and most likely your home, of fleas.