If Looks Could Kill — Francine Pascal

The Wakefield sisters are determined to keep their New Years resolution.  Even if it kills them.

Identical twins Jessica and Elizabeth Wakefield have always considered themselves best friends, but lately they've been acting more like best enemies.  So they make a New Year's resolution:  no more arguing or disagreeing about anything.  

Jessica forces herself to gush over Elizabeth's new blouse, even though it's the dweebiest thing she's ever seen.  Elizabeth pretends she's thrilled to run into Jessica and her Unicorn Club friends at the movies, even though the Unicorns are the snobbiest girls on the planet.  And when adorable Eric Weinberg moves to Sweet Valley, the twins decide they can both have crushes on him.

Jessica and Elizabeth will always be sisters...but will they always be best friends?