Singers are like athletes – they need to warm up before they perform. Warm-up exercises will make sure your voice is ready to perform.

Rebecca Lodge – BBC Choir Singer shares some tips.

Warm up your voice
Warm up your voice to avoid straining and damaging your vocal cords. Always take a deep breath before you start and try yawning – yawning opens up your throat and helps your voice resonate.

Exercise 1

Breathe out through your mouth releasing all the air from your lungs.
Once your lungs feel completely empty, relax your stomach muscles, open your mouth and let the air flood back in.
Do this several times.
Now breathe in again and when you release the air add an ‘sss’ sound. See how long you can hold it.
Try this again using ‘shh’ and ‘fff’ sounds. This will help to build different vocal muscles.
Exercise 2

Close your eyes and spend a little time breathing in through your nose and out through your mouth. (When singing, you should breathe in through your nose and out through your nose and mouth.)
When breathing in, imagine the breath going down into the lowest part of the lungs, keeping the shoulders down and relaxed.
When breathing out, try to maintain your inflated shape, breathing out slowly until you feel as empty as possible.
Exercise 3

Counting four, breathe out whilst you bring your left ear down to your shoulder.
Counting four, breathe in and bring your head up to the starting position.
Repeat with the right ear.

http://www.bbc.co.uk/sing/learning/warmingup.shtml