As with all products, hair growth products work for some but not everyone. Certain ingredients like silicone, zinc, Vitamin B, Keratin, Proteins and Aminos all help the hair grow. Try find a product with good reviews.

I have quite fine hair and the best brand i have ever found is Nioxin. there is a shampoo, conditioner and scalp treatment, it noticeably improved my hair. it made my hair shiny and smells nice and minty too :)

You’ll have to try and see which one works best for you but, yes, body-building shampoos are specially formulated, and contain proteins that bond to hair in order to bulk it up (they literally make each hair take up more space, and stand that tiny bit apart from the hair next to it, hence increased volume). Other ingredients that help enhance hair volume include dimethicone copolyol, a silicone derivative and PVPs (polyvinylpyrrolidones) which coat the shafts, to make every strand that bit thicker. All of these may well lead to some residue building up on your hair, so don’t use them continuously.

No. They're all rubbish.