Sing with proper posture. Your shoulders should be relaxed and slightly back. The jaw and muscles in the mouth should be relaxed. Ensure that your jaw is slightly dropped and not sticking forward when singing. Your feet should be approximately shoulder-length apart when standing. It is rare for a vocalist to sing sitting, but when sitting, sit up straight toward the edge of your chair with your feet planted squarely in front of you.
Identify the vocal register you sing in naturally and then use that information to select vocal repertoire that fits your voice classification. Begin on the lowest note in your range and with a piano, sing in half steps up to the highest note in your range. Take note of the highest and lowest notes to determine your range. A soprano will have a range between middle C and A or higher above the staff. An alto will be able to sing from G below middle C up to at least an F on the top of the staff. Tenors will sing approximately an octave below sopranos, and baritones an octave below altos. Basses are the lowest voices.
Expand your vocal range by practicing appropriate vocal exercises. Begin on a middle C if you are a soprano or alto, and a fifth lower if you are a tenor, baritone or bass. Sing five notes ascending from your starting pitch, and then return to the original pitch. Then, begin a half step higher and sing another five notes. Continue this exercise until you reach the highest notes in your range. Do not sing higher than is comfortable to avoid harming your voice.
Monitor your diet for anything that will dry out your voice. Proper nutrition will help to keep your vocal cords lubricated and ready to sing at a moment notice. Avoid drinking caffeine several hours before you sing. Caffeine will dry out the vocal cords and dehydrate the body. Alcohol should also be avoided for the same reason. Milk and cheese can create extra phlegm that will impede your singing and cause straining in the voice.