Use a dramatic red, white and black color scheme that reflects the covers of the Twilight series. You can also incorporate the cover imagery in an even more explicit manner with the following ideas:
Twilight's Red Apples
Use a large black or white bowl filled with red apples as decorative focal points.
If you're hosting a sit down dinner, pin a place card for each guest into a red apple and place it in the center of their plate.
If you have a self-serve buffet, label the dishes with a red apple pinned with a card that describes the dish.
New Moon's Ruffled Tulip
From an online or local wholesale florist, order a few dozen stems of red and white stripe ruffled tulips.
Use them as centerpieces for a table, or use them as place cards by putting one stem on each person's plate with a name card attached (use a red ribbon like on the cover of Eclipse).
Let each guest take one home at the end of the night as a favor. Place them all in a large vase with very little water (so they aren't soaked when guests remove them) by the door. Tie small thank you cards to each stem with a red ribbon.
A Red Ribbon Eclipse
Order a large spool of half-inch-thick red ribbon that is the same shade as the one on the cover of Eclipse.
Use red streamers to hang across the room, mimicking the cover.
Tie napkins, favor bags, place cards and thank you notes on using the red ribbon.
Chess Pieces from Breaking Dawn
Create a dramatic centerpiece by placing a chess board in the middle of the table with only the white queen and a pawn on the board. If you can, paint the pawn red.
Send guests home with travel-sized magnetic chess board games.
Purchase enough white queen pieces to use them as place cards for guests. Write each guest's name on a flat place card, aligned to the right. Then, glue or tape the place card to the bottom of the chess piece (aligning the chess piece to the left so you can still see the name on the card).