We've been giving our dog brewer's yeast and garlic supplements, which definitely takes care of fleas- she's played with my partner's brother's dogs who are covered in them, and we even had an outbreak with our cats from which she emerged unscathed. OTOH, we've pulled eight ticks off her already!
I've looked at the chemical stuff, and I'm not happy-- I would be especially concerned if I had kids. I know that people rub herbs on their pet's fur, or you can also rub brewer's yeast in. I think it's also important to feed a healthy diet and supplement with fatty acids, etc.
My vet recommends a pretty thorough brushing once a day, especially after they've been outside playing in tall grass to get the ticks to drop off. Since our dog is white and loves to have her belly rubbed, it's easy for us to do a pretty thorough check each night too.
No easy answers, I suppose.... I've been considering getting the Lyme disease vaccine for our dog and just living with the ticks (which, let me just say is hard, because the little buggers scare the daylights out of me.....ew!). Hope you find a good solution!