Find your singing voice. There are several ranges of singing voices, including bass, baritone, tenor, alto and soprano. Find the voice that's closest to your natural speaking voice. You can do this by playing notes up and down the scale of the piano. Sing along with the notes, and when you find you can no longer sing along with the lowest note, write it down. Write down your highest note, and you determine your voice range. The most comfortable area will probably be in the middle somewhere.
Practice good posture. To do this, stand up very straight and stick your chest out a little bit. Keep your shoulders back and your hands either directly at your sides or behind your back.
Practice proper breathing. This involves using your diaphragm instead of your chest. Inhale quickly, making sure to keep your pallet open, and get the air all the way into your stomach. When exhaling, your stomach should be clenched, and the air should be moving out of your mouth -- from your stomach -- slowly. Proper breathing is essential, and should be studied thoroughly.
Practice vocal warm-ups and exercises. Practice warm-ups before each time you sing, and practice exercises in between singing live or recording. A simple vocal warm-up includes humming up and down the major scale. Your mouth, nose and throat should vibrate if you're doing it properly. After singing up the C major scale, sing up the D major scale, then the E major scale and so on. Go as high as you can, and then sing back down the scales. There are many different vocal exercises that are helpful, most of which use the solfege syllables: do, re, mi, fa, sol, la ti and do.
Avoid smoking, drinking carbonated beverages and drinking caffeine. Drink plenty of water. It's also important to refrain from eating and drinking too much dairy, as this causes your body to produce excess mucus. In turn, you may find yourself clearing your throat a lot, which will irritate your vocal cords. Remember, your voice is your instrument. You must maintain it by staying healthy.