I don't do anything special, really. I trim about 1/2" three or four times a year. I don't use shampoo - only CO wash, and as the others have said, I detangle very carefully - only when drenched with conditioner while in the shower with a wide toothed shower comb. I never comb or brush other than that.
Oh yes, and I eat pretty good - lots of protein. I am 56 so I didn't think I could grow it as fast as I have. Patience it foremost. It takes time to grow your hair.