As was stated above: Training "smart" resistance training will definitely help. So will plyometrics. Above and beyond that, I would definitely emphasize flexibility and form.
As a reference, let me suggest the following book: The Complete Master's Kick
by, Hee Il Cho. It breaks down individual kicking techniques, specific resistance exercises and stretch for each kick also. I know there aren't a lot of TKD fans on the forum now a days, but if you want to learn kicking skills you can't go wrong.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto