This product will only work on blonde or bleached hair. The shade of your hair before you use it will determine the shade it comes out as. So if your hair has been lightened to a dark blonde and you use the silver it won't make a slight bit of difference, however, if you have a mid blonde/ginger colour and put a red over it, it will come out red, maybe not bright red but still red. Your base colour is really important. If you want to go blue or teal but have yellow hair you may well end up with green hair as the blue combined with yellow makes a more green colour then a blue. If you use one of the reds that is pink based, it will not bleach out in most cases and will go salmon pink, the best way to get the reds out is to use the Colour B4 remover stuff. If you have almost white or white hair the white toner will work as will the silver, if it's yellow it probably won't. Ignore the 15 minute directions, leave it on for as long as possible, sleep in it if you can, it's just a vegetable conditioning dye it haas nothing in it that will make your hair fall out so the longer you leave it on the better condition your hair will be and the more your colour will stick. The darker shades lighten up and the lighter shades just wash out very fast. If you have a colour that is difficult to keep in like red or lilac, make a big pot up of one third hair dye and two thirds conditioner and use that instead of regular conditioner to keep your colour topped up. Avoid sulphate based shampoos as they will drag the colour right out. I have been using these dyes for ten years and used most of the colours. You used to be able to dilute directions with regular conditioner and that wouldn't affect the colour but they changed the formula. Now if you dilute it with conditioner you will get a paler colour which is good if you can't find a shade that is quite what you're after. This advice works for pretty much all similar dyes such as Renbow, Manic Panic and Stargazer. Hope this helps.