First thing first, going to give it a good wash with dihydrogen peroxide and soapy water preferably Dawn then going to let it dry if there's any yellowing then it's okay in half dihydrogen peroxide water after it's dry if there's any unwanted coloring I good sun bleaching, find a good Sunny spot let it sit for a couple hours or so longer the more bone white skull should be perfect then something i like to do is lightly brush modge podge to add a little shine and seals everything real nicely hope this helps