The most important factor, when choosing a freestyle scooter for a beginner rider is it's height. The overall height of the scooter should reach somewhere up to the waist and hips.
To choose the right height, use the size chart, which you can find as a part of product page of each scooter. The size chart includes recommended height of the rider based on the recommended height of the handlebars and the overall height of the scooter. For more information visit article how to choose freestyle scooter.