If you wish to use the mask as symbolic of Romeo, perhaps a consideration of his character traits will assist you in the construction. For instance, since color is always symbolic of psychological and emotional state, painting Romeo's mask in bold colors such as red and purple which suggest his passion and impulsiveness as well as his noble stature may be appropriate. Streaking the colors across the mask will also indicate the impetuosity with which Romeo acts.
In using such bold colors and strokes, you will also wish to avoid creating a mask that suggests a villainous character, however. Maybe adding stars in white for the star-crossed lover and other light colors will alleviate the suggestion of any evil. A heart in the corner with Cupid's arrows may also help.
A mask of Romeo...interesting assignment. If we are talking about a physical mask that looks like him, I would choose a boyish look, maybe with bushy hair. A modern look could be someone like Justin Beiber. I also attached the poster from the original move below.
If you want more of a visual representation on the mask, Romeo is a charmer. He is in love with being in love. He is a smooth talker and a hopeless romantic. The mask could be a collage of these personality characteristics in Romeo. I hope that leads you in the right direction. Have fun :)
He looks the way you want him to. There is no specific/ detailed outline of what he looks like or what he represents. tRY TO INCLUDE SOMETHING ABOUT LOVE AND DEATH MAYBE?