Drink plenty of water every day, or beverages that are free of caffeine and alcohol. Alcoholic beverages and drinks like coffee and tea have a tendency to dry out the vocal chords, and the larynx needs to be thoroughly hydrated in order for the voice to maintain its health and strength.
Practice breathing exercises each day. Breath in deeply through the nose, and place one hand on your stomach and the other on your chest to feel the air expanding these parts of the body. When singing, the stomach should "swell" with air, making it easier for you to execute the notes and produce a stronger sound. Breathe in and out by making a vowel sound to work on breath control and and articulation. This strengthens both your singing and speaking voice, and teaches you how to pace your breathing and articulate properly.
Exercise regularly, and try singing and speaking while performing cardio workouts that involve running on the treadmill or elliptical machine. Working out opens the airways and strengthens the vocal chords, and will give you more endurance when making lengthy speeches or holding notes for long periods.
Purchase a humidifier for your room to add moisture to the air. This makes the voice sound especially pleasant and lubricates the vocal chords to make the voice stronger and maintain its health. Humidifiers are also ideal for people who have to sing or talk often, since we naturally breathe through our mouths and this makes the vocal chords dry. Taking a warm, steamy bath or shower for at least five minutes twice a day will produce a humidifying effect as well.
Record yourself singing or speaking. This will help you assess your strengths and weaknesses, so you'll know which vocal execution skills to work on. Take care to full enunciate words, e.g. don't drop the "g" from words ending in "ing," and pronounce the "t" at the end of words and phrases. Keep recording yourself until your voice is pleasant to listen to, and you can understand your words clearly.
Take acid reflux medication if necessary, since this condition can weaken the voice and produce a gravely, dry sound in the throat. Talk to your doctor about which medicines are right for you, and make dietary changes like reducing acidic foods like citrus fruits.
Stop smoking if necessary. Smoking weakens and swells the vocal chords, and dries out the larynx. Stay away from second-hand smoke if possible to keep the voice strong and healthy.