After you simmer (not boil) as others have suggested, be prepared for most of the incisors and maybe K9's to fall out. The lower jaw may also separate in half. Afterward, I use Volume 40 peroxide, and will sometimes dilute it to 50/50 if I don't have enough peroxide to cover it. I collect the teeth and put them in a small separate tupperware container to peroxide. I usually soak the skull in the peroxide solution for 3-5 days. Keep in mind, volume 40 is about 12.5% peroxide, so a 50/50 is about 6%. The more you dilute it, the longer it takes. Afterward, rinse it good and set it outside in the sun to dry, it'll whiten right up. Also use gloves and wear safety glasses when handling the volume 40. You don't want it on your skin or in your eyes. I use superglue to put the lower jaw back together, and elemers glue to put the teeth back in.