Natalie Portman will guest-judge on 'Project Runway'

Actress Natalie Portman will help Heidi, Michael and Nina decide who of the 15 remaining designers are "in" or "out" on Wednesday night. The theme is "green."

How to woo Portman? Here's a cheat sheet for contestants:

Favorite designers: Lanvin (she wore it throughout her stint as a judge at Cannes this year), Zac Posen, Helmut Lang.

Don't incorporate: Bacon as trim. Portman is a strict vegetarian and even has her own line of vegan shoes with the label, Te Casan. In fact, her collection is on sale right now -- including this dainty style, Perla, selling for half-off at $171.50. (Animal prints are highly discouraged too.)

Fun fact: She does a killer Lily Tomlin impression. Who knew? Um, Natalieportman.com -- natch.

photo: Valery Hache for AFP