Make sure you have a lot of redundancy when securing it. Don't just secure it once and assume it will stay; secure it in more than one way.
Some ways you can secure it, that I can think of, is:
1.Getting some of those clear straps (usually for bras and such) and attach one to the sides of the mask and loop it under your chin like you would a bike helmet (you can pull some of the wig in front to that it would look natural.
2.Gluing A LOT of bobby pins or hair clips to the bottom of the mask and clipping it to the wig.
3.Getting some strong magnets and gluing one magnet to the bottom of the mask and glue the other one on your wig cap. (You may want to use multiple magnets)
4.Super glue it to the wig itself. (Ok, that was a joke, but still you can do it...although I would not recommend it.)