Yikes! Jealous! You guys all have gorgeous hair - but how do you grow it? How often do you cut?

My hair recently had a big issue and I lost a lot of it and want to cut it, but now that I know the issue, I want to grow it long and healthy -

Any tips???
3b/fine/normal porosity/normal elasticity

LOVES behentrimonium methosulfate
(don't ask me to pronounce that!)

Want to grow it long again!
And simply want to figure out this hair of mine!