Not only is this not a "one size fits all" sort of world, it is also a "nothing, with the possible exception of water works for everyone" sort of world. And, even water seems to differ for many. Some love hard water, some love soft water, some use filtered/distilled water on their hair. You will see a broad spectrum of commentary on every conceivable product/ingredient/method out there. We can start with our hair properties to try to narrow our choices, but inevitably we will still have to experiment to find which things will work for us for ourselves.