Firstly, I would like to thank Falken76, as his original predator mask helped me to get my butt into gear and learn how to model more organic objects. I've been making sci fi ships and that sort of thing for years and his original mask helped me greatly get the sizing right for the eye sockets and such.
Print standing upright, I suggest 2 shells but as far as infill, that's up to you. If it's going to be used as a mask, I would do 10% or 20, but for decoration go for 0% infill, it prints like a dream.
Supports and Rafts are needed but they are very very minimal when they print and are super easy to remove.