I'm not a hair vitamin pro, but I'll help you out to the best of my ability that I can. If anything I list is incorrect and anyone notices, please please please feel free to intervene.
Okay, first and foremost, we all need a multi-vitamin so that we can get all the required nutrients to lead a healthy life. For general hair condition, many board members here and on other boards take the GNC UltraNourishHair, GNC's NourishHair or the Vito Vitamin. They contain, Biotin, MSM, Silica and other vitamins which are important for hair health, stimulation and growth.
I started off with the NourishHair first to see how my body would react. So far I haven't experienced any complications.
Biotin:
Biotin can boost your hair growth. Skin, nails, and hair rely on biotin to grow, your hair should grow faster and stronger. Many board members have experienced results using 5000mcg/day.
MSM:
It helps to decrease hair fall out. It does this by assisting in making the growth stage of the hair longer. The longer you are able to retain the root, the longer you hair will grow. Many board members take up to 3200mcg/day.
Silica:
Helps your hair be soft and shiny. I believe the average dosage could be 500mg/day
Evening Primrose Oil:
Can reduce PMS, clear up eczema, helping your skin glow, minimize fine wrinkles, reduce cholesterol, help with your metabolism, and cure hair and nail problems. It helps nourish straw-like hair. It should help your scalp should feel less dry and the hair growing in should feel softer and more nourished. You should use this in conjunction with Flax Seed Oil because your body need both to work properly. Taking both will help the cells of the body work more efficiently and in return help growth of hair as well as health of hair and body. I believe people use 500mg/day.
Flaxseed Oil:
Same benefits as Evening Primrose Oil. I believe the usage is 500mg/day.