Clear Voice Advice for Singers

Try to warm up your vocal chords with voice exercises before singing. Maybe sing a few notes of the musical scale or "la la la la" in an modulating manner (i.e. low rising then lowering, etc.). Try to build up the strength of your vocal chords just as if you were physically exercising. Start moderately before singing for a long time.

Andy Serkis who voiced Gollum in the Lord of the Rings trilogy (actually he wasn't used in the first installment) said he had to drink a mixture of honey, lemon and ginger tea (I might have the combination wrong) everyday because he was straining his voice by speaking with a rasp.

Whitney Houston would drink honey, lemon tea before her performances.