Hitting the road?
Before you do, take everything out of your car and vacuum and wipe down everything inside. A microfiber cloth and a little water can go a long way (and add a little Armour-All if you want to get fancy). Then put back everything you know you'll need, like jumper cables and other emergency supplies (like roadside flares and a first-aid kit). Other must-haves (even in your everyday life) are paper napkins, plastic utensils, and rags (perfect for catching crumbs in your lap, among other things).
Organizers (seatback model pictured above), available at major retailers or online, make travel essentials accessible to you and your passengers. Once you're on the road, dispose of trash daily so it doesn't pile up, or worse, attract bugs.
Up in the air
If you're traveling by air this summer, every ounce counts. Again, start by emptying your handbag, messenger bag, backpack or briefcase. You'll probably see things you can throw away or file: old receipts, candy wrappers, movie tickets, etc. Next, look for things you know you won't need on your trip, like membership cards for local stores. Consider using a smaller bag. If you're using a larger bag, consider using an organizer inside to find smaller objects quickly. I use one in my airplane tote bag, and it's fantastic. Also, I recommend a very small bag for the day of travel that holds nothing more than your wallet and mobile phone. Everything else can be in a larger carry-on. Also consider using a bag that closes securely with a zipper or snap and with a strap long enough to go across your body so pickpockets can't easily grab it.
What's in your wallet?
One more place to reduce bulk. Pull out all those old receipts, business cards from people you met months ago, and membership cards you won't be using. You can likely do with far less than you're carrying now, at least while you're out of town.