First, don't throw out that empty Pringles can. Dump the broken chips and wipe down the inside with a baby or cleaning wipe. Allow it to dry, then throw it in your beach bag for future use. Its great to conceal cell phones, room keys, money, etc. It also keeps them dry and free of sand.
If your family uses Crystal Light flavor pouches, don't throw out those containers. They are great as a sunglass holder, cigarette case, skim board wax holder, or to toss in that jewelry you forgot to take off, for holding sunscreen sticks and any other tiny objects you don't wanting lost in the bottom of your bag. The uses are endless. They are air tight when lid is secured and great for keeping water and sand out. Though, I wouldn't recommend throwing it in the water.
Keep a small container of baby powder in your beach bag. Sprinkle some over your sand covered family to soak up excess moisture and make the sand easy to brush off.
And my favorite beach tip . . . the MacWagon. This thing collapses and expands; great for traveling. Big rubber, large tread tires are great for pulling over the sand. Throw in the beach chairs, small cooler, umbrellas, beach bag, wake and skim boards and head to the beach. Its a little pricy but well worth the investment. Great for the kids' ball games, camping, working in the yard and for any event you have a lot to carry.