There are some dance classes that insist that the dancer be 11 years or older before she can dance en pointe. The instructor needs to ascertain that the young dancer's feet, legs, and ankles are strong enough to handle the stress of dancing on her toes.
Having said that, as a young dancer gets closer to graduating to pointe shoes, there are some things she can do to prepare. Her feet and ankles need to be strong, she must find perfect balance, and she must practice separating the movements of different parts of the body.
A correctly pointed foot should be straight down the inside of the calf, from knee to toe―no curving the foot inward, even though it makes it easier to point. Winging out to the side is fine for experienced dancers, but should not be the focus for intermediates. Toes should be flat, not curled, and the bottom of the foot should form a banana-like curve along the natural arch. Try pointing and flexing in a TheraBand to build strength.