to get it healthy? try not to straighten it .. ik it will be hard but i havent straightened mine for over a year now and it is very long and healthy. this will also give you some free time to discover new types of hairstyles with heat!
Dont use any hot irons. It damages and breaks down your hair. I have absolutely beautiful, very long, healthy hair and do you know my secret? Dove. In my opinion, it's the best shampoo ever made. I'll list what it says and the ingredients. Dove is therapy for your hair. It has nutritive solutions with serum. It is advanced care and Repair. It has water, sodium sulfate, benzine, Dioxide, and many other things. I'd but it and check the bottle. It's effective against all hair symptoms. I'd recommend the cool moisture one. I love the way it leaves my hair feeling refreshed. It's like it's on vacation! You dont even have to buy conditioner with this shampoo!
If you have thick hair use Pantene brand 2 in 1 (you can buy it at target walmart harris teeter and cvs ect) it really helps. Also even though its good to wash your hair dont wash it every night or it will break down and get dry and rough. I hope this helps