trishgl,
For my dog I always used Frontline, only because it worked on him. Some people use the Advantx II products, but that did not work on my dog.
I didn't like flea collars, because when my dog played he would get it caught on branches, and other dogs often grabbed ahold of the collar, trying to tug it off him.
I am like you I hate the chemicals.
A friend of mine said putting cider vinagar in their dogs feed helped ward of fleas and ticks. It did not work on my dog.
Another thing sometimes when they load up with fleas and nothing works to get the fleas off, your dog might have a health problem that need attention.
One friend, her retriver was loaded with fleas and they went to the vet, turns out the dog had a growth along its spine.