Are flea collars the most effective way to prevent dog fleas?

The good news is that getting rid of fleas on dogs is a fairly simple process: you kill fleas and then do not allow future fleas to return to your dog's coat. The bad news, of course, is that it requires work. Getting rid of fleas on your dog forever is not a one-time process; instead, it requires a consistent, multilateral approach. This means that in order to completely get rid of fleas, you must not only clean your dog of fleas but also focus on cleaning your entire house of fleas. What for? Even after you kill the fleas that currently live on your dog, they can return if there are fleas left in your house to roam freely. And no one wants to deal with a second or third flea round.

I can recommend this flea collar to prevent dog flea as follow:
http://www.buychina.com/products?keyword=flea+collar&cid=

at the same time, you should wash your pet per 2 or 3 months

They are a great tool in preventing fleas; however when used alone, flea collars are not the best form of protection for your dog. Flea collars are great when used alongside other topical flea control products.