Stand up straight with your shoulders relaxed and level. Concentrate on relaxing the muscles in your face and neck. Tilt your chin inward slightly and open your mouth by dropping your jaw in a relaxed manner. If you have muscle tension when you sing, you won't be able to achieve the optimal quality of tone for a falsetto voice.
Breathe deeply as you sing. You need plenty of air to support your tone when you are singing falsetto.
Imagine your voice beginning in your upper abdominal muscles and flowing straight to your face and the top of your head. Your abdominal muscles support your tone and breath control as you sing, and your voice should resonate in your facial cavity when singing falsetto rather than vibrating in your chest.
Raise the rear portion of your soft palette as you begin to sing high notes. You can do this by imagining that you are beginning to yawn.
Sing in a high tone that sounds much like a woman's higher vocal register. If you are unfamiliar with this sound, listen to music that features falsetto singing and try to imitate what you hear.