From my experience in dying, If it's a darker color fabric, the color may be a little darker when you dye them..Like with me, I had a grey sweater I needed to dye navy blue (the closest color you could get) but it still has a slight hint of grey in the navy blue (the color it SHOULD be, oddly enough), but if it were white, I already know it would have been the shade I was originally going for..
Oh! Almost for got, I wouldn't bleach them. A lot of people say that bleaching things doesn't always get them all over the same color and it will be blochy, which you don't want..In turn, when you dye it it will be different shades in random spoits..
Cosplay DA Regular DA
-Fate Testarossa (Mahou Shojo Lyrical Nanoha A's) ~90%-
-Ryouko Ookami (Ookami san and her 7 companions) ~75%
-Amy Sorel (Soul Calibur) 25%-