Just about any method will cause the teeth to fall out at some point. Boiling makes the bone more brittle and nasal material will come out. I like detail and will not boil a skull. Masceration is my 2nd favorite method and it also works on the degreasing process as well, you will have teeth typically fall out doing this. They go back in quite easy. Beetles are my favorite and most hands off, so to speak. After taking them out of the beetles I just degrease them for however long they take.
When whitening a skull, DO NOT USE BLEACH. That will deteriorate the bone.
I use a couple of different things. IF you have a pool supply store, you can get baquacil oxidizer, it's 24% peroxide works well. I also have some 50% peroxide that I use as well. You can also go to the beauty supply store and get some volume 40 creme and basic white. The volume 40 is a 12% peroxide and the basic white is a developer/carrier. I mix that up, put it on the skull very liberally and wrap in saran wrap, put in front of a heat source. I put mine out on a glass table. If you put in front of heater of some sorts, be careful not to get it to close so the saran wrap doesn't melt.
If you need to replace teeth, you can use regular ol elmers glue. It dries clear and works well. I usually dilute the elmers and put it in a spray bottle with water. I then spray it on every skull. I'll use it to replace any teeth that have come out as well.
Once the skull is completely degreased (to your liking) and then whitened, I use a product called paraloid to seal them up. You can also use a Krylon matte finish sealer, found at hobby lobby to seal them. It works well also. Make sure to get the non-yellowing stuff.
I'll be happy to answer any questions or help, if you need it.