Drink some warm tea with honey for one minute to help physically warm and lubricate your vocal cords.
Use one minute to run through a breathing exercise to help calm you down and get your air flowing. Breathe in for four seconds and take the air into your diaphragm; breathe out for eight seconds. Complete this exercise three times and then rest for 12 seconds.
Spend one minute buzzing your lips on major scales. Start with a C and sing in whole notes at just faster than one beat per second. This will make it possible to sing two complete scales.
Allocate two minutes to singing the beginning of your piece. This will help get you ready to perform.