Hair Growth Remedies

I used to blow dry my hair all the time until I realized it gave me split ends and dryed out hair. Now I let my hair air dry all the time, but I want to let my hair grow long. I was wondering if air drying hair is good for hair growth?

A friend of mine wants to grow her hair longer. I want to give her tips on it but i dont have enough. I wonder if there are any easy, cheap products you can use to improve hair growth and stop it from breaking. Are there any? If so, can you give me the names? Any help, tips, advices or personal experiences are welcome!
Have a nice day and thanks for answering!