1. Keep your arms slightly away from your body. Clasp your hands out in front of you or bring your arms to your sides and a bit forward, raising them about 6 inches in a flexible, relaxed fashion. This will allow your ribcage to fully expand and your lungs to fill to capacity. More air allows you to project your voice more strongly and clearly.
2. Keep your feet about shoulders' width apart. If you like, one foot can be further forward than the other. Make sure you're solidly balanced, but still flexible. Slightly bend your knees. If you must sing while sitting, make sure both feet are flat on the floor, with 12 inches or so between them, and that you're sitting up straight, but not stiffly.
3. Relax! Tension destroys vocal tone. Try not to let your shoulders hunch up and keep your neck from tensing. Don't force your chest up and out when you breath in. This will actually constrict your air flow. Stay in motion, however slightly. This will relax your body and your tone will sound more natural. Try gently swaying from side to side with the rhythm. You'll look better, too!
4. When you inhale, push your stomach out. This will allow you to more completely fill your lungs. As you exhale, bring your stomach slowly in, using the muscles of your diaphram (which is just under your ribcage) to control your tone.
5. If you have to hit a high note or you hear yourself singing flat (that is, if your notes are a tiny bit too low), raise your arms a little higher and smile slightly. For very high notes, try closing your eyes and turning your face up slightly.
6. Conversely, if you start to sing sharp (a tiny bit too high), bring your arms down a little lower and open your mouth slightly wider by dropping your lower jaw. Don't dip your chin towards your neck, however, as this will cause your air flow to become constricted, which will show up in your voice.
7. Find your natural volumn. Many people sing too softly, out of shyness or embarassment. This keeps them from being able to support a good tone. Others sing as loudly as possible, which can result in sharp or flat notes, as well as body tension. Singing at your natural volumn should feel good, not forced or constricted.
8. Find your best tone. Tone is strongly affected by your state of mind. You may find that you sound better when you imitate someone else, like an opera singer, pop diva or rock star. Have fun experimenting and don't hold back! You may be surprised at just how good you can sound.
9. Enjoy yourself! If you take all these tips to heart, singing could become a habit.