My hair has always been a strange combination of dry/soft, I blame my heritage but I'm probably just extremely lazy. You can actually see how dry it looks in photos.
I take good care of it, I wash it, brush it, have it trimmed monthly and I hardly ever dye my hair and if I do I use restoring shampoos and conditioners and yet it still comes out dry and dull.
I once complained to my hair stylist about it and she told me running cold water on it while you wash it can help out, she also told me not to brush it while it was wet, avoid using hot instruments and excessive dying, try to keep your hair down [apparently if you put it up too tight it causes damage].
Apparently coconut oil is good for it as well
Unfortunately none of the above works for me, my hair just gets extremely greasy or drier than ever.