Place your arms slightly away from your body while you sing. Put your arms at your sides and pitch them forward slightly. Alternatively, clasp your hands in front of your body and raise them a bit. This position will help your ribcage to expand fully and fill your lungs with air. Increased air enables your voice to project clearly and with strength.
Stand with your feet shoulder-width apart. Bend your knees slightly and balance yourself in a solid fashion while remaining flexible. If you're sitting while you sing, keep both feet flat on the floor and sit up straight in a relaxed manner.
Relax your muscles. Tension can be detrimental to your tone. Forcing your chest out and up as you exhale will only constrict air flow. Maintain slight motion while you sing -- for example, sway with the rhythm of the song. This keeps your body relaxed and helps your tone to sound more natural.
Push your stomach out as you inhale to fill your lungs more completely. Using your diaphragm, allow your stomach to slowly move inward as you exhale. This will help you to control your notes and improve your singing voice.