There are many simple practical techniques that can be applied to take better care of the voice and avoid voice strain. They include:

• No smoking
• Avoid shouting or straining the voice
• Drink lots of water to hydrate the voice box
• Moderate use of alcohol and caffeine, which cause dehydration
• Schedule periods of the day with no talking to allow the voice to rest
• Sip warm water, tea or juice when possible to soothe the vocal chords
• Swallow carefully and avoid repetitive clearing of the throat
• Treat coughs as soon as possible and try to minimize hacking coughs
• Proper posture

National Institute on Deafness and Other Communication Disorders
http://www.nidcd.nih.gov/health/voice/takingcare.asp