This shape?  http://www.123rf.com/photo_15534848_mas … fence.html

Personally, I find chicken wire hard to work with and almost impossible to get smooth.  I've never made a mask that large, but I would make a mold out of cardboard, cover it with a sheet of thinner plastic (Visqueen), and make the actual mask on top of that, then remove it from the mold when dry.

Lay down a piece of cardboard, and draw a whole-face mask outline on it, then draw a line to form the partial mask, but don't cut the excess off, as it will provide stability.  This part is just the base of the mold that you will form the actual mask upon.

Decide in the beginning if you want the eye hole cut out, or just painted black.

Using either styrofoam, pink foam insulation (easier to cut than styrofoam-- use a serrated knife), or wads of shaped newspaper taped down firmly, build up and shape the brow, forehead and nose.  Step back and squint at it to make sure it looks right.

Then cover it with thin plastic and tape it down.  If you have a roll of double-stick tape (sticky on both sides), line the eye sockets with that and press the plastic sheeting down to it.  If the tension is too tight and the plastic won't go deep enough, carefully slit the plastic with a knife and press it to fit; add a small piece of plastic to fill the gap, so it's all covered with plastic.

If you need to, redraw the mark for the cutaway part, so you'll know where the working edge is.  You only need to lay the papier mache to the line, but if you have some trouble doing that, work past the line and trim it off later. 

Let me give you a real-life tip:  the more carefully you work on the surface, the smoother you lay the paper, the more wrinkles you avoid making, the better you burnish the layers down, the smoother your final surface will be.  If you're fast and sloppy, you'll have to sand down the entire surface, and that's a lot of surface you'll have there, and a lot of work.

Brown wrapping paper or brown paper bags would probably be best for your base layers of papier mache (PM), and white glue diluted half/half with water would be an adequate adhesive.  Try to avoid pieces of paper so large that any part of any piece wrinkles -- cut to shape if necessary, and overlap the edges, pressing those edges down firmly to avoid edges as much as possible.  If you really need that wrinkle, slit it with a craft knife and overlap the two corners.

If all your PM paper looks the same, it's almost impossible to tell if you've got complete additional layers.  To avoid that problem, use plain brown paper first, and when you're ready to begin the next layer, use either white kraft paper (it's just bleached brown paper, but more expensive), or take a felt marker or a little quick-drying paint, add daub quick marks all over the brown paper; and then, when you've got the second layer down, check for gaps showing plain paper and cover them.  Alternate all the next layers until you think the piece is strong enough to maintain its rigidity.  If some areas (like across the eyes) seem weaker, add more layers there.

Once you've decided the mask is rigid enough and dry enough, look it over carefully for rough spots.  If there are wrinkles or raised edges of the paper that lifted up as they dried, wrap a piece of sandpaper around a small block of wood, and sand down the high spots.  Work carefully and don't apply more pressure than is needed.

Finish the raw edges by wrapping a thinner type of paper over the edges from front to back.  Again, avoid wrinkles.  If you decided to cut out the eye, wrap those edges, too.

When dry, again look for irregular spots that need a touch of sandpaper.  If you will need to affix this mask to another object, apply your attachments or drill the holes when the main layers are finished and dry, but before applying the finish layers.

Now set the mask back down on the mold, and apply several layers of thinner paper for the finish layer.  This can be newspaper or another kind.  Again, try to avoid wrinkles, and take care to burnish down the paper well, esp at the edges, so they don't lift up as it dries.  The more carefully you work, the better your results will be.

When the finish layer(s) look right, let it dry thoroughly.  Placing in front of a fan so the moving air passes over the piece will accelerate drying.  When the top seems dry and the piece is rigid, carefully remove the mask and turn it over so the surface that was on the plastic has a chance to dry, too.

Now brush the whole thing with several coats of acrylic gesso, or (cheaper), plain white* acrylic wall paint (emulsion).  Thinner coats are better than heavy coats that sag as it dries.  If the coverage isn't good enough to cover minor imperfections, you can thicken it by adding powdered chalk (calcium carbonate, aka agricultural lime) or gypsum, both of which are found cheapest at garden stores or pottery/ceramic-making sources.  Add a bit at a time until it looks right.  Too much, and it may crack as it dries; you may want to experiment a bit on some stray pieces of cardboard before you use it on your mask.

Be aware that if you don't protect the raw inside of the mask from moisture, it will absorb it, even from the air, and your mask will start warping.  I would advise you coat it with both the basic acrylic paint/emulsion, and then the sealer (shellac or varnish).

If your mask may be exposed to the weather or other source of moisture, you should probably coat it with several layers of shellac or varnish (real or synthetic).

* If your mask is going to be a dark color, you can use a darker paint.

Sue

I made a very large skull in paper mache. I started with a base of cardboard, scored, folded and glued together for the basic shape.
To add more shape to it I used crumpled newspaper and spray foam insulation.