Halloween masks of the 70s and 80s were plastic store-bought variety, but prior to that, folks made their own masks often times. Some of the masks they came up with were very unsettling. I believe they are much scarier than any "realistic" werewolf and clown masks of today.
Part of the charm was that these masks were vague. What exactly where these people dressing up as? And the emotionless blob-shaped faces were robotic and unsettling. They were just enough human-like but then something "other" that was indistinguishable.
The basis for a mask is easy. Craft stores and even online at Amazon, you can get a basic mask to work with.
You will want to texture it. This can be done with strips of cut fabric like an old t-shirt, and a mix of half Elmer's glue mixed with half water. Dip the strips, take off excess liquid, start slapping them on the mask. You could also use newspaper instead of fabric, or cheesecloth if you want a weird texture, even pantyhose for fine pores and burlap for large ones. You could also apply plaster of paris, but it will make the mask heavier and not so flesh-like.
Be as creative as you want.
You could even use autumn leaves that you will later paint over top of when they are dried in place. When you are done decoupaging the layers, paint some extra glue-water mix on top, smooth it out, let it dry well a few days.
So far as painting goes, I'd consider painting the mask black. Then once it's fully dry, dry brush something like a dingy brown or rust atop of that and then add another dry brush layer of a bluish or greenish flesh tone atop. You could go for the all-one-tone look of simply painting it a dirty ivory, letting the weird textures show through. You can cut the eye holes bigger, put black makeup around your eyes so they are nothing more than dark voids within. You can even utilize crackle medium (found on the acrylic paints aisle of the craft store).. I used it for this plague mask (bottom layer black), then crackle medium, then khaki. Once all that was dry, I dry brushed rush into crevices.
If you don't want texture, consider a doll's face-
Paint the mask a skin tone. Give it rosy round cheeks like a doll's. Give it long lashes and red heart-shaped lips. Then, take black paint and a finely-pointed brush and make squiggles for cracks in the white surface.
Consider putting cutting the edge off a styrofoam egg carton crate to make an eyelid to glue over one eye with lashes on it, for that doll's closed eye look and one good eye still working...
Here are some more masks to ignite your imagination. Remember too that using old sacks, yarn hair, and paper bags were big in those vintage eras -
Construction paper with a string and yet so freaking creepy (above)
Remember how effect the Michael Myers mask was? Simple William Shatner mask painted white. By taking out detail landmarks we expect to see in a human face, it was made quite frightening in its blank stare-
- Movies with creepy masks -
Saw
Halloween
The Strangers
Alice Sweet Alice
Texas Chainsaw Massacre
Scream
You're Next
Tourist Trap
Terror Train
Night Breed
Silence of the Lambs
Valentine
Trick R Treat