There are a bunch of studies done on hair follicles, and it is already understood that hair follicles do not actually die the way we used to think they do – but the problem is the fact that they stay dormant, and this can be genetically pre-programmed, although there are some ways to handle it.
Stopping the further fall of hair is easier than regrowing; although if you aren’t fully bald, then even regrowing some amount of hair is possible (some percentage of it at least – from studies conducted).
Science has figured out ways on how to regrow – but they are still developing a possible cure to baldness once and for all – and if you can hold onto the amount of hair you already have, by doing various methods (such as the ones listed on this article here), at least until the actual cure is released.
I know, staying youthful is hard work, and you have to constantly work hard towards it – but also without anxiety and worry (as those too are one of the biggest enemies to hair loss).
One most important thing discussed in the article link given above, is scalp massage; this is a key in keeping the hair you already have, and possibly re-growing more hair.
There are many methods – the point is to build a regime, and do what you can to stay healthy, including plenty of exercise and emotional stabilizing exercised (such as meditation) – if you look at people who meditate more often, are often in a more relaxed daily state, and also look years younger; this is no accident – it is a side effect of meditation (because meditation is done for larger purposes than just youthful looks, obviously).
So if you are looking for a sure-way to keep hair; then the least you should do is scalp massage on a daily basis.