Adding hand gestures to songs can be a participatory event. For the song "Wade in the Water," for example, simply ask the children what motions would work for the phrase, "Wade in the water." The children will suggest some ideas for movement, and they will all be good. The motions might involve hands, waists, arms, legs, and facial expressions. Through the process of consensus you will agree on a suitable gesture. Make sure the gestures are respectful of the tradition from which the song comes; be careful not to trivialize the tradition with the gestures. (More on body movement later.)
The children's participation in shaping the music brings the music to life. As with all creative activities, be very positive. Do not allow any child to be negative in any way. Creativity flows in a positive environment; it ceases in a negative one.