I started off with just a blonde dip dye, pre lightened and pre bleached ends.
I then applied the product Crazy Color by Rembow in Lavender to the blonde ends of my hair while my hair was DRY. This is important as dye sticks better to dry hair.
I literally left it in for 5 minutes, no longer, and rinsed! That's how easy it is. It's very important you apply this to pre lightened hair and only leave it for 5 minutes or else you will get a much darker color result.
It's very simple and it's not a big commitment to pre lightened hair, as the color is pastel so it can be easily bleached out.