Keep your shirt on to help conserve body heat. Obviously, this depends on the temperature of the air and water where you are boating as well as the type of clothing you are wearing. However, a shirt can act like a wetsuit top and help to trap heat inside next to your core.
Use your clothes to help you float. Take off your pants and tie the legs together using an overhand knot. To fill them with air, lift them over your head behind you and quickly bring your arms and the pants forward toward the water. They will fill with air and can be used as a buoy or float aid. Jeans are especially good, but this works with other fabrics as well.
Take off your shoes. It is difficult to tread water and stay afloat with weights strapped to your feet. If your shoes float, you can put them under your armpits to help with flotation. If they are heavy, they may sink, but it is better to lose a pair of shoes than your life.
If you can find something floating in the water like a log or a large piece of debris, climb onto it and use your clothing items as a paddle or sail to help propel you along in the water.
When your boat’s driver or other boaters come to your aid, they can use a piece of clothing to reach out to you and help pull you into the boat. Reaching out to a person is the first step in the “Reach, throw, row, but don’t go” steps for rescuing someone in the water.