Like a runner must warm up her legs, arms and core, a speaker or actor must warm up the muscles involved in speaking. Warm-up exercises include massaging the jaws in a downward motion, opening and closing the mouth, and blowing raspberries, vibrating the lips. To warm up the tongue, close your mouth and move it in a figure eight pattern. Move it as far to the top, bottom and each side as you can while you do this. You can also place your tongue behind your bottom teeth, let your jaw drop and push your tongue out, stretching it. Repeat a few times.
Stand with legs shoulder-width apart, shoulders back. Relax your muscles. Take inventory of your body by closing your eyes and thinking about each part of your body. If there is tension in a body part, take a moment to consciously release that tension, relaxing the muscle. Once you've released the tension, take a breath from your diaphragm and make a sound. The goal is to let the sound "fall" out of you, rather than forcing or projecting it. Continue with this, elongating the sound each time. Focus on supporting the sound with your breath so it's not forced out of your body.
For a more intensive breath support exercise, take a Shakespearean sonnet and try to read each stanza in one breath. Once you can perform this comfortably, move on to reading two stanzas per breath, then three. For a more advanced option, recite Gilbert and Sullivan's "Modern Major General" lyrics.
The following exercises can enhance and even increase your vocal range. Perform a vocal slide on "ahh." Begin with the lowest you can go, then slide slowly up until you've reached the highest audible pitch you can muster. Rest a moment, then reverse the slide from highest to lowest. Repeat a few times. Changing the vowel sounds will help stretch your range, as it responds differently to various vowel sounds. Be sure to take a huge breath for this one. If you run out of breath, take a breath and start on the pitch you paused on. Continue sliding up or down.
Another exercise involves pulling in your lips over your teeth. Your mouth will be closed, but not tightly. Make humming noises in different pitches until your lips tickle slightly. Hold that pitch. Continue searching for other pitches and frequencies where this occurs, and hold those pitches out.
Enunciation exercises focus on tongue and lip agility, consonants, vowels and resonance. For tongue agility, repeat the phrase, "Adults who play table tennis are extremely fit." Focus on the movement your tongue makes, making sure not to slur. For the lips, recite, "Betty plays competitive badminton." Focus on bringing the lips together with purpose. Repeat the phrase over and over. Tongue twisters like "unique New York, unique New York, you know you like unique New York" help with consonants. "There isn't enough space in this place for a race" will exercise your vowel pronunciation. For resonance quality, repeat the phrase, "Swimming is fun in the summer months." Hum the "m" and "n" sounds, focusing on making your lips tickle.