o.k. so I have written hub on this but for packing to travel light on a motorbike. Best idea I have used is to roll your clothes and then pack the item into airtight bags. Works a treat and saves space!
Pack as much lightweight and dry foot in as many nooks and crannies in your baggage as possible. Take crackers, oatmeal, granola bars, dried fruits, etc. Naturally you can bring fresh fruits, meats or vegetables.
It's much cheaper to bring food on a trip than buy it at major tourist destinations.
Take your suitcase out a week before your trip and start placing items you want to take with you (like your swimsuit or beach hat) but don't need before the trip in your suitcase. This makes packing so much quicker and and easier. Also, it prevents you forgetting anything important.