A long time ago, it didn't matter how many suitcases you brought along on your trip. Sizes and weight weren't much of a concern, either. But in this modern era of security checks and surcharges, it's best to plan a minimalist approach to luggage, bringing only what you really need (or less). Thus, packing for a trip can be a cause of great stress.
But it doesn't need to be, if you put some thought behind what you're bringing, why you need it, and how it's being packed. In the article, 15 Packing Secrets From a Professional Traveler by Nora Dunn (not the former SNL performer), you'll find some great tips on packing lightly from someone who literally lives out of a suitcase and travels the world full-time.