Dropped Coin Method
This method works well for children between the ages of about 5 to 10 by fixating the child's eyes upon one focal point and compounding suggestions of heaviness.
Give the child a shiny coin to hold and have the child's arm stretched out directly in front of him.
"Hold the coin between your finger and thumb and keep holding it there, with your arm stretched out, whilst you listen to the sound of my voice.
Now an interesting thing is going to happen. In a few moments you'll notice that arm becoming heavier and heavier whilst at the same time it begins to feel relaxed and comfortable.
And as you notice the growing sensation of comfort within you, that arm gets heavier and the hand and the fingers begin to feel like lead weights - so heavy, so comfortable and so relaxed - and as soon as that coin falls from your fingers and touches the floor/your lap (depending where hand is) - you will go into a wonderful deep gentle hypnotic rest.
And the arms and the hands and the fingers are getting so wonderfully heavy as you go deeper and deeper into hypnosis."
As soon as the coin drops from the fingers and touches the floor/lap/etc. (timing is crucial here).
"That's right - just falling down and down into a gentle hypnotic rest.
From this moment on - every word that I say is a total part of you and goes deep down into the wonderful part of you that controls the......" (adapt here according to the problem).