This party theme almost decorates itself. Use bright, primary colors in your tableware, and don't forget to add some prominently displayed serapes, sombreros and piñatas to the decor. Have some mariachi music playing in the background to serenade your guests, and don't forget to serve lots of chips, salsa and guacamole. If you're taking the party outdoors, string red chili pepper lights around the perimeter of your deck or patio, and use dried chili pepper garlands and wreaths to create some visual interest on your buffet or table. Whip up a few pitchers of margaritas, too. The señors y señoritas are bound to get thirsty before the evening is over.