How to not get split ends.?

my hair isnt really thick. but for some reason i have the type of hair tht gets split ends easier. i want to be able to uze heat tools like everone else and they domt get hair damage. i straighten my hair mabee like once every three months. i want to do it more without getting so paranoid about getting split ends. a heat protectant barely helps. if i straiyen it once i get a ton of split ends. i want ky hair strong healthy and unbreakable and i wantt to be able to use heat tools more often and not get paranoid and know my hair isnt going to break. HELP!!