I tried giving Lulu small amounts of crushed garlic with her food daily to help with the fleas. She liked it a lot, and didn't have too much of a garlic breath. She didn't have any negative reactions to it either. I read in several places, including "Puppies for Dummies" (which is a great book on puppy housebreaking, and I warmly recommend it) about giving garlic as a supplement to fight fleas. However, other resources say garlic, as well as onions are harmful for dogs.
Eventually I became too lazy
and started giving Lulu a regular flea + tick medication. However, I still put a few drops of Lavender and Eucalyptus essential oils on her collar and in her detangling spray to keep the fleas away.