For me:
1) Avoid tension on the scalp.
No tight hairstyles like braids or supertight buns. (Works for others, but it's not for me.)
2) Scarf everynight.
This is my least favorite part of my hair routine. I tie the scarf so that it's right above my eyebrows so that there isn't tension on my hairline.
3)Wash often.
Dirty hair breaks. At least mine does. The cleaner my hair is the better and stronger it feels. This is also why I don't use leave-ins or oils.
4)K.I.S.S.
I know a lot of ladies here enjoy their hair routine, but I'm not one of them. (I don't hate it, but it's like brushing my teeth. Something I have to do that I don't relish.) I cut out everything that isn't necessary, so that I can get it over with. That way I won't get lazy and blow the whole thing off. It's also easier to integrate into my life. I hate planning my life around my hair and spending all Saturday on my hair. That's not for me, but a lot of ladies here view it as pampering themselves, like a spa day.
5)Rinse the relaxer out like there's no tomorrow especially concentrating on the scalp.
6)Have a prove it attitude towards damage.
I never trim 3 or 4 inches off because of damage. I don't really know what damage is besides heat damage, and when hair is heat damaged it breaks off so no trimming needed. I could ask 10 experts if my hair is damaged and get 10 different answers. So, as far as I'm concerned, if it doesn't break off, then it isn't damaged and I'm not trimming it. I self dust my hair every other month, that takes care of split ends and the fact that the right side of my hair grows faster than the left.
7)Lye relaxer.
It made a huge difference for me, but everyone feels differently about this issue. My sister still uses no-lye and doesn't have the dryness, frizzy ends, and reddish discoloration that I was having. But for me, lye relaxer was a huge turning point.