Garlic is brilliant, our dog doesn't mind it, but our cat curls his nose up, wouldn't go anywhere near it.
However, we have been "flea-free" for several years
without using any collars, powders, frontline, or any other thing you can buy from your pet shop or vet.
The only thing I do on a regular basis is put a tiny amount of Neem Tree Oil on my hand, rub them together, and then let your hands slide through their coats. It does "pong" a bit, but it is brilliant, effective, healthy, edible, skin healing, etc, etc.
You can buy pure Neem Tree Oil from some good reputable Oil Suppliers.
If your doggy needs a wash, all you need to do is add a tiny amount of the Neem Tree Oil to their shampoo and it will get rid of all the fleas, ticks, etc, etc.
It doesn't kill the fleas as it isn't toxic, but it stops the flea's reproductive system from working, very clever, and very safe! Insects don't like the smell, a brilliant repellent, even for garden pests!
If you have kids, a tiny amount in their shampoo will prevent any nasty creepy hair visitors as well!
Cardamom.