Start an intensive deep-conditioning regimen the week before bleaching your hair. Look for a cholesterol-based conditioner, an inexpensive ingredient that you can find most beauty supply stores. The day you bleach, glop the conditioner on your hair that morning, put on a shower cap and sit under a hood dryer if you have one. At the very least, leave the conditioner on for twice as long as recommended on the package. Rinse it out before you apply the bleach, and do another application after bleaching.
Pour a packet of bleach powder into a plastic mixing bowl. If your hair is particularly long or thick, you may need two or more. Remember that you're going to have to really douse your head with the stuff, so be generous.
Add the recommended amount of hydrogen peroxide by measuring it in a measuring cup first. The strength of hydrogen peroxide liquid developer you use should be determined by the color and condition of your hair. Very dark hair may need a 30-volume hydrogen peroxide developer, while lighter or damaged hair often only needs 20-volume. "Volume" refers to the concentration of peroxide in the developer. The weaker the solution you can get away with, the less damage to your hair. Ask the salesperson at the beauty supply store for help choosing the correct volume for you.
Stir the bleach powder and peroxide with the hair dye brush until it assumes the consistency of whipped cream. This should take around 10 seconds.
Brush the mixture onto your head and wait for the fun to begin. The color will begin to lift out of your hair quickly, so check it often and rinse it out as soon as it's white. You can apply a toner over your freshly bleached hair to give you a more natural shade of blond, or keep it white and rock the Edie Sedgwick look.