Hold your arms away from your body to allow your ribcage to become fully expanded. This can be done by clasping your hands in front of you or raising them about 6 inches from your sides in a relaxed fashion. The more your ribcage can expand, the more air can fill your lungs.
Adjust your posture so that one foot is placed slightly in front of the other and both feet are about shoulder width apart. Hold your shoulders back so that you stand straight up, and hold your chest high to allow it to fully expand.
Relax your face and jaw muscles and concentrate on avoiding tensing your neck and shoulders as you sing. Use the rhythm of the song to keep you calm and sway with the music.
Push out your stomach as you inhale then bring your stomach slowly back in with your diaphragm as you exhale. Use these upper abdominal muscles to control your tone and volume.
Turn your face up to reach higher notes. This motion increases air flow. Avoid dipping your chin because air flow then becomes decreased.
Find a voice volume that is comfortable for you to achieve. Singing too softly diminishes your ability to hold a tone; however, singing too loudly can cause your voice to become out of tune and leads to upper body tension.
Practice consistently. A good beginning routing consists of 20 to 30 minutes per day of singing scales. This practice not only strengthens your "singing" musles and improves voice control, but also builds your confidence, which also works to make you a better singer.