Choosing a first pony
Older is better
A first pony should be at least twelve years old: it has seen everything a child can do, and forgives most of it.
Size
For a child under eight, a Shetland of up to 10 hh is plenty; children from eight to twelve suit ponies of 12 to 14 hh.
Temperament before looks
Ask to see the pony caught, tacked up and ridden by its current rider before you ride it yourself.