Hi and welcome to Crackster!
I can't remember the Zeffirelli mask, so I'm kind of at a loss for what to suggest...
What material would you like to make the mask out of?
Would you like it to be decorative or wearable (and if wearable, how often and where - meaning, how sturdy/waterproof/comfortable, etc?)
Laminated paper is a great starter method for getting into maskmaking, cheap too! I use brown paper shopping bags and good old Elmer's. Here's a link with some good info - scroll down to where it says 'Papier-Mache' http://www.squidoo.com/maskmaking#module1460028
- this is basically the method I'm referring too, though when I do it I use my fingers and apply straight glue (not the 50/50 glue/water) to the paper and smooth it in place.
This method also assumes you have a form to work from - you can also start with a band around your head, with crossing strips to form a crown, and strips glued end to end coming down across your face to start building up the front.
grrr - sorry I can't 'splain better - I just moved and can't take pix or scans to make this more coherent! I'm happy to walk you thru some tips if you want, feel free to PM me - I've made dozens and dozens of masks this way (and it just occurs to me I never posted any here...) and it's a great method.
BTW - the above link mentions 2 books that I consider my BIBLES! It's the first two on her list:
The Prop Builders Mask-Making Handbook by Thurston James
Maskmaking by Carole Silven
The James book can be hard to find (and pricey!), but I just peeked at Amazon and they have lots of copies of Carole's book used from about 4 bucks!!! Do yourself a HUGE happy service and pick up a copy, I go back to it every time I feel 'dry' in inspiration, and it's a great jumping-off point.