Search online or in the yellow pages for dancewear boutiques. Then, call ahead and ask if they sell ballet shoes for kids and adults.
Once you are in the store, ask for ballet shoes in your shoe size or your child's shoe size. If you're shopping for a child, you should have the child with you. Use your shoe size as a guide. This will let you know whether or not you need a bigger or smaller ballet shoe size. Make sure that you do not purchase shoes that are too small. The leather on ballet shoes stretches--but it will not stretch a size up.
Make sure that you have a little room at the top of the toe of the ballet shoes. This will make it easier when you are pointing your toes and dancing in class and in performances.
Purchase shoes that have an elastic band already attached. It can be a pain to sew on an elastic band after you have purchased the ballet shoes.
Purchase shoe materials that fit with your life as a dancer. Canvas ballet shoes can wear down quicker than leather, and are often less popular among dance teachers. But, they are often more popular with dancers who do a lot of performances with a partner. Canvas ballet shoes also work better on vinyl floors. Leather ballet shoes are often more durable and last longer than canvas shoes.