Redtape, regular brown bottle peroxide will work good. Just check on it in a couple days to so you don't get it too white for your liking.
It a horned skull?
Yeah a lot of people told me to get the strong peroxide from a beauty supply store, but I figured the regular brown bottles would let me whiten it just the way I wanted.
It was a horned doe (horns are approx. 2.5-3 inches). Those definitely took a little extra work to get them off, but it wasn't too bad.
Simmering worked pretty good. My dad caped out a doe skull from ML season and buried it in the garden to see how the bugs work.
ETA: Do you put any type of finish on them? I was thinking a thin coat of clear, Krylon spray might be a good idea. Never tried it though.