The best packing advice I ever got was from my dad. He told me that before each trip I should think of the essentials that must be brought for the trip to be a success and pack those first. Everything else you can live without or buy if necessary. So for most trips it will be your passport, money, camera and medications. Then of course if you are going for something like a wedding you will want to tack on “wedding clothes” or if its a beach trip you can include “bathing suit.”
Once those essentials are in the suit case, everything else is just gravy (pretty important gravy, but still).
My next trick is to keep a travel drawer. I keep this drawer filled with things that I need and use when I travel as well as clothing that I have brought on previous trips that I have been glad to have packed. Examples of things in the drawer: Water Shoes, flashlights, gloves, travel bottles of aspirin, wet wipes, my passport, camera connectors, electric converters, water proof fleece, travel sleep sack. When I start packing, its easy to open this drawer and look at the things I might need. It also helps to jog my memory on other things I might want to grab (“oh I won’t need my water shoes because its winter, which reminds me I should bring my extra warm socks”).
As I start pulling aside items for the trip I like to lay out everything on my bed in order to get the big picture. This often helps me realize that I am trying to pack 10 white t-shirts when really only 8 are necessary (I kid of course, you really only need one or two). I also like to take this opportunity to check the weather forecast and try to realistically imagine wearing each item in that climate. I tend to get cold easily and so I pack extra jackets and warm clothing that end up being super unnecessary – this is how I ended up bringing a jacket and fleece pull over to Israel in August (wasted packing space).
My final tip is to take a look at what you are packing and think if anything can be subbed out for something in your closet that you don’t like or plan to donate soon. I try to bring anything from my “goodwill” pile that could replace something I really like. That way if its ruined or lost no big loss. Also, in a pinch these things can be left overseas if you find your suitcase is too heavy or too packed.
Once everything is laid out on the bed and mentally approve I assemble it in my suitcase (more in this later) and hit the road.