M.L.
I'm a hairstylist. Prenatal vitamins give great results to hair and nails. There are some great natural 'masks' you can do on your hair too, like with honey and olive oil... just google for recipes.
http://www.livestrong.com/article/13896-hair-care-recipes/
http://www.livestrong.com/article/116500-natural-home-rem...
I also recommend Sebastion's Potion No 9, it's a moisturizing, conditioner+styling aid, great for thick, wavy hair. Just apply it after you get out of the shower to damp hair.
Also, regular trims will help with the health of your hair, as will using heat protectant sprays prior to flat ironing/curling. If you blow dry your hair, don't use the dryer until your hair is about 75 % air dried. Keeping your hair out of tight hairbands and ponytails, especially when wet will help prevent breakage.
You can also get a glaze for your hair. John Frieda has shampoo in glazes in clear and brunette. I prefer the salon quality ones, but those work pretty well too.