a. fold the sides and "cheeks" in to the proper shape.
b. Fold the forehead and chin behind a little bit, tuck in the eyebrows to expose some black paper, and slightly open the eyes in a sly expression. Give him some wrinkles by his eyes.
c. Continue to shape the face until it looks like V's mask. Feel free to make changes, modify and improvise this to your own delight. As long as you don't cut, you're cool. Google Image search is your friend. So am I, but I won't be able to answer individual "how did you get past step 'n' "-type questions.
Thanks for watching, and I look forward to seeing your origami V faces everywhere!
For larger images:http://chosetec.darkclan.net/origami/diagrams/vendetta