Brainstorming
Before you start writing your packing list, think about where you are going, whom you are going with and how long you will be gone. This will help determine the things you will pack and how much of a particular item you may need.
Must-Haves
Although there is no truly universal packing list, every traveler should have a few items. Depending on your destination, these may include sun block, a passport, ID documents, an insurance card and time killers such as magazines. However, many you may be able to buy many necessities at your destination.
Making Room
Don't just think about what you'll need on your vacation but also about how much room you have in your luggage. You may want to pack light. Most airlines charge baggage-check fees, and you'll probably want to leave room in your bags for any souvenirs you find on your trip.
Checking It Twice
Once you have a good idea of what you need, make a packing list. Don't throw it away when you're done packing. Instead, keep it and update it for upcoming trips.
Learning From Mistakes
If you took a lot of clothes on your last trip that you barely wore, pack less this time. If you lost your digital camera in the water, bring a waterproof disposable one.