Keep your electronics (and everything else!) sand and water-free! Before you go anywhere near sand, put your smartphone in a ziploc bag. The screen is still responsive to touch, but you wont risk it getting water damage or scratched by the inevitably sneaky sand. Other bags can be used for wet clothes or swimsuits after the beach or carting shampoo, sunscreen, lotion, etc. in your beach bag safely so it doesn't leak everywhere.