Well, it wasn't me, Fuzzle Guy, it was my friend Sapphire. I'll ask her your questions, though. :)

First, my roommate put two layers of plaster gauze strips on my face
and the top of my head(I used plastic wrap to prevent it getting
stuck to me, and a shower cap, leaving the nostrils and eyeholes
uncovered. When it dried, I could remove it, and had a base for the
rest of the mask that would fit snugly.

Then, I put a layer of paper mache over it, to build it up. This I
don't think was entirely necessary, looking back on it, but it
smoothed out some of the plaster lumps, and is lighter than plaster.

for the eyes, I used some cotton stuffing wrapped in plastic(but you
can use any round object) and formed clay around them, leaving the
stuffing in there to stop the eyeball from sagging. It sits just
outside of my real eye, so that I could use the wrinkles to sort of
hide that. I used clay to form the shape I wanted for the face (my
nostrils are inside the mouth) and smooth the head out. I also
added clay ears.

http://www.deviantart.com/deviation/11605141/

Then I painted it with acrylic, two layers, and added details and
fixed some things I didn't like about the mask.

http://www.deviantart.com/deviation/11679249/

For the ponytail, I cut out the pattern in fabric and stitched it
shut, then turned it inside-out and stuffed it. Sharpies worked
well for coloring, but do it somewhere ventilated... yikes.

Glue it on, plus stitches, and voila!