Hide Belongings in Food Containers at the Beach
I try to take as little as possible with me around cities with high theft rates, but I'm always going to need my keys and a credit card or cash. So when I'm at the beach, where I may not have an eye on my things at all times, I hide my stuff in food containers. Pringle cans, Cheez-It boxes, cookie bags, etc. Anything that isn't clear, obviously.
You can also use empty sunblock bottles, but then you have to clean it out before you use it.
Put your Cords in an Eyeglass Case
It will keep your cords organized and protected.
Use Pill Cases for Organization
A weekly pill case isn't just for daily doses. Separate your different pills (i.e. multivitamins, allergy pills, pain relievers, Dramamine, Airborne, etc.) and re-label the case. Or use it for earrings, rings, spices (seriously), and other small objects. You can also use contact cases!
Hide Cash in Sanitary Napkins
Men are deathly afraid of period products. Your cash is safe.
Waterproof Fabrics with Beeswax
Rub your shoes, backpack, or any other fabric with beeswax to weatherproof them. Keep in mind that they won't breathe as well afterward. (Details here.)
Plastic Wrap Your Liquids
Unscrew the cap of your bottles, place a layer of plastic wrap over the opening, and seal it by putting the cap back on. It will keep any liquid from leaking out if the flip-top pops open.
Charge Electronics Through the TV
If you lost or forgot your wall plug, use the USB port on the television to charge your devices.
Cover Razors with Binder Clips
Do you ever fumble around in your bag, drag your fingers across a razor, and wish it were acceptable to toss your razor and be a hairy beast? Yeah. Cover your blades, people.
Sort Earrings in Buttons
Fasten a set of earrings through a button to keep them paired and organized.
Russian Doll Suitcases
If you plan on bringing a lot of stuff back with you, pack your things in a small suitcase, then put that small suitcase into a larger one. That way you'll have an extra suitcase for your trip back.
Put Bar Soap in Your Dirty Laundry
If you have some funky clothes, put one of those cheap hotel soap bars into your dirty laundry bag to help cut those nasty smells. You can also throw a dryer sheet in with your clean clothes to help keep them smelling fresh.
Bring Laundry Detergent
If you're planning a long trip, take a couple ounces of laundry detergent with you. You can use it in a machine or hand wash your dirty roos in the sink.