The basic Curly Girl method.

Others have explained this better than I can.  Most notably, Lorraine Massey in the Curly Girl book.  But there are some pretty good summaries here and here.

To summarize:  stop shampooing and stop brushing.  And stop blowing it straight and flatironing. And start deep conditioning.  Easier said than done, right?

If your hair is long enough, stop there and start wearing it up as much as you can, at least for a while.  My hair is always in the best condition when I wear it up as much as possible.  And I can even throw extra oil in it and have it not look gross.  

If your hair isn't long enough to wear up, read on.  There are styling products and diffusers.  I don't particularly think these are damaging, if the styling products are carefully chosen and the diffuser is set on 'cool.'  Drying alcohols are bad; heat is bad, but these are not found in good stylers and diffusers that are set on 'cool.'

I'm trying to wear my hair up as much as I can, but I still like it down with the gel and diffuser sometimes.  Otherwise I miss my curls.  What's the point of having them if I can't ever see them?