Use natural reflectors

When shooting at the beach, the white sand will act as a giant reflector if the model is sitting down and close to the sand. When shooting in the city, the top of a silver trash can lid can be a reflector. When shooting near the water, the water can act as a reflector. Remember that the sun is not the only light source. In fact, sometimes what the sun is reflecting off will throw more light on the subject than the direct light from the sun.