I was just talking about this with my vet last week. Get Frontline and get it from your vet. There are other flea & tick repellents available over the counter with the same medication as in vet-supplied Frontline but they won't work as well as the prescription kind (& I can attest to that!). Although the medication itself is the same, the application method and absorption vehicles are different -- and they don't work anywhere near as effectively. Yes, you can have some success in reducing the number of ticks with these other products but, especially if there are a lot of them (& we live in a VERY tick-prone area) these other products aren't going to really, effectively do the whole job. If you want to be totally sure you get maximum Frontline absorption (especially if you have a medium to long haired dog), clip or shave a small space on your dog's back between its shoulders & apply the Frontline there -- just a small 1-inch x 1 or 2-inch space.
We're a "kids & critters" family (with various kids, grandkids, dogs and horses coming & going) and spend a lot of time outside. Frontline on the dogs is the best way I've found to protect my whole family.
Not sure how things are in Florida, but in central Massachusetts we had such a mild winter that there is already a tick explosion here. In addition to Lyme disease (a big problem in our area), there are a number of other tick-borne illnesses that can cause a problem for animals and for people. Ehrlichia is one, but there are more -- and none of them are fun, though many are treatable with a course of doxycycline.
Good for you for being on top of this!