I use Frontline Plus during flea and tick season. Truthfully, I still occasionally find ticks on him so it's not perfect. I live in a very tick infested area at least it has become that way in recent years. The Frontline seems to work really well. Chance never has fleas.
Your best preventive is daily checking with a fine-tooth flea comb. There are no side effects and you get to check your dog every day so you will notice right away if something is amiss. There is nothing like hands-on every day.
With my German Shepherd who was prone to getting fleas (and allergic to them), I also did the daily checking and used a flea powder but I don't remember which brand. It was quite a long time ago.
Frontline Plus is what we have always used too, but for whatever reason this season we have had a lot of the tiny "sand" fleas and frontline doesn't seem to help. Vet recommended Actyvl and we have been on it for one month. Got rid of all the fleas, so likeing this. Same price as our Frontline Plus.