One trend I have noticed is most airlines have seriously reduced the number of direct flights, so depending on where you are coming from and your timeline you may want to buy sooner as opposed to later.
And by reduced, I mean I looked at flying from Philadelphia to Orlando, and out of 13 flights each day, 3 were direct, and 3 required more than one stop!
Its frankly not the most fiscally responsible plan but gets you from point A to B the fastest. Years ago we would wait and look at prices but you may end up with a journey easily taking 2-4 times longer.