If you don't have issues with high blood pressure, please try rubbing a little essential oil of Rosemary into your scalp each day. Works wonders. Whenever my hair begins to thin out the slightest bit, I run for the Rosemary bottle, and notice amazingly fast results. But, it is not recommended for folks with high b.p.
Also, I second the advice of a previous poster who mentioned Biotin. Biotin makes your hair grow like crazy, PLUS it very effectively delays the graying of your hair.
Horsetail (the herb - available as capsules at herb stores) really makes your hair healthier and stronger, as well.
About 10 years ago, I lost a lot of weight as well as a lot of hair as a result of the weight loss. My stylist recommended Nioxin, and it worked fabulously for me. I've just gotten into the herbal / natural thing since then.