search around on here, or google.

don't strain your voice too much though, that would end up badly
take large breaths from your diaphragm and sing from your stomach to support your singing, not the throat. sing scales while playing them on the guitar and gradually build up your range and stamina.
Be sure to sing from your diaphragm as much as possible. It takes the pressure off of your throat.

Warm up....don't just try to hit high notes right away.
Drink lots of water.

There's also a variety of concoctions you can make to help.

I like hot water, honey and a little bit of lemon juice. It sooths your throat and helps break up phlegm. Halls cough drops work too.

Oh and if you smoke either quit or cut back (if you can do this tell me how )
Sing in your vocal range, sing from the diaphram (thats what makes it carry without blowing out in one song), Do vocal exercises (should be able to google that). I've also heard lemon juice helps yur throat. Don't try and sing a whole set list without doing some training for a while. Warm up your voice before singing.
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