Sleep for seven to eight hours a night. When your entire body has had an adequate amount of resting time, it prevents your voice from sounding hoarse or crackly or from sounding oddly higher than normal.
Speak in a standard "indoor voice" volume when talking to others. Don't yell as that strains your vocal chords.
Rest your vocal chords for two to three hours a day where you don't speak. This will help recharge your vocal chords during the day, preventing raspiness.
Drink at least 64 ounces of lukewarm water per day at the minimum. Plenty of water will prevent your vocal chords from feeling dry, something that can cause raspiness. Avoid any substance with caffeine, such as coffee, soda, certain teas and other drinks.
Keep a humidifier in your home. This will help the air in your home stay moist, keeping your skin and vocal chords moist as well. Move the humidifier to your nightstand while you sleep.
Speak from the diaphragm when you do talk. This will prevent the strain on your vocal chords.