One thing to know about the beaches of Rio is that each has a certain appeal to various groups, but all beach goers in Rio observe certain niceties and good sense guidelines.
Rio residents wear outer clothing on their way to the beaches. Women in particular wear something to cover their almost-there beach wear. They usually carry a large tote bag with all their necessities for the day. Men who wear boxer type swim suits can manage with a shirt.
Take very little money or vluables to the beach. There's no reason to tempt a thief and why ruin a good day at the praia?
Taking sports equipment. Frescobol rackets, a volley or soccer ball, a bodyboard or surfboard are ususal.
Take your camera and use it, but observe the usual precautions of sand, water, sun and thievery.