Just a taste...
Sara Petrosky has four rules of thumb to get your creative juices flowing:
No. 1: Go for a simple color palette. Petrosky prefers green, white and burgundy for the holidays.
No. 2: Use no more than three different botanicals in your arrangements. In fact, think "monobotanical" (no more than one type of botanical per vase).
No. 3: Always use fresh, quality products, like those you find at a florist. "To me, using fresh product seems outside the-box, because everybody uses artificial," Petrosky said.
No. 4: Use a variety of surfaces, vertical and horizontal, on which to place your arrangements.