This post doesn't just apply to flights or car rentals in Florida, many of the things I write here will apply to many destinations.
Keep in mind, I'm sharing what I've experience personally, but you may have had a totally different experience, feel free to share your own tips in the comments below!
I started keeping an eye on flights to Florida about 8 months before we traveled. In my opinion, there is such a thing as booking too early. The flights 8 months ago were pricey. We looked at travelling from our home airport in Saint John, New Brunswick (Canada) and we also considered a few U.S. airports within driving distance (Bangor, Maine and Portland, Maine). In past years, we always found flights were significantly cheaper flying out of the U.S. but this year was different, we were travelling during Spring Break. For this reason, flights were more expensive across the board. So we went in to it knowing we would spend more than we had in years past. This would be true of other busy travel times such as Christmas and Thanksgiving.
Despite airfare prices being more expensive 8 months out, I do recommend at least having a look at prices once you know you are travelling. You can start seeing when prices start going down. Kayak features on their website a little tool that indicates the likelihood of prices going up or down in the next 7 days as well.
In terms of helpful websites, I have typically found that booking through the airline directly is cheapest. Even if it isn't, many airlines offer "lowest price guaranteed" offers, so that if you book with them, and you find the exact same flights on another site for a cheaper price, they will match it and/or offer you some kind of discount or rebate on a future booking.
In our case, the cheapest flight appeared approximately 8 weeks before our intended departure date. We ended up finding a flight out of our home airport for just slightly more than one of the U.S. airports. Bonus!
My biggest tip when you're planning your trip, is if you can be flexible on your departure and return dates, be flexible as long as you can - occasionally it can be significantly cheaper to fly on a particular day of the week. We have found that Tuesdays and Wednesdays are the cheapest times to fly, and the cheapest day of the week to book is usually Tuesday, late afternoon, because a lot of carriers release their seat sales at that time.
As for a rental car, my experience is the longer you wait, the better price you get. Especially if you aren't stuck on a particular type of car. We booked our rental 2 weeks before our trip. We had booked a minivan, which two weeks before we booked was priced at $950 for 2 weeks. I ended up getting the rental for $450 (taxes and fees included) for two weeks. Not bad for Spring Break.
Have questions about how we got our deals? Leave me a comment in the section below. Or, feel free to share your own tips and tricks.