There are a few things you'll wanna do:
#1. Use a shampoo that has no sulfates. Sulfates are found in cheap shampoos. They are abrasive salts used to cleanse the hair but they do serious damage to the scalp and hair in the process.
#2. Start taking Elon Matrix 5,000 vitamins. These vitamins have biotin in them, which Dermatologists have found to help in hair regrowth. From what I have read about this product it helps rebuild the follicle and strengthen the hair. From using the product I know it works. My hair is thicker and healthier now than it has been in years. The company also has a nice sulfate free hair care collection that I use because I loved their vitamins so much I figured I would give that a shot and it's great especially when you have dry hair from straightening or blow drying.
#3. If you perm your hair ... don't do it as often. If you dye your hair with bleach to get a lighter color... don't do it as often, try alternating between a darker color in the winter and a lighter color in the summer. Use highlights for a lighter color instead of an all around blonde.
Hope this helps! GOOD LUCK!