How do you stop hair from getting dead ends?

My hair is very thick and wavy. I've been trying to let it grow longer (its about shoulder length now) but I can't because it always gets so dry and dead that I cant stand it. It's not really about split ends, my hair just gets dry and frizzy and damaged. I've tried using good conditioners, but that doesn't help. The worst part of my hair is my bangs! they are so dead I can't even curl or straighten them anymore because they just dont respond to anything...help me!