How to sing a scale without having your voice crack

[edit] Intro

Are you tired of having to stop singing because your voice keeps breaking? This will help you.

Before you sing, drink some water. If you are going to a concert then hold a teaspoon of olive oil in your mouth. Swish it around your throat to make your throat relaxed.
Don't over-practise. Practising to much can damage your vocal chords. If you are preparing to perform, you don't want a sore throat!
Hum. Hum the scale so you know what you want it to sound like.
Sing! Start out soft, and work your way up.