One mistake parents often make is trying to prevent their child from experiencing disappointment. Yes, it's difficult to see your child hurting when she doesn't get invited to a birthday party or he doesn't make the baseball team. You may be tempted to call the parent and the coach and ask why your child wasn't included or even give them a piece of your mind.
Stop for a moment and think about it. What message would you be sending to your child if you tried to heal that disappointment? How is "fixing" things for your child going to help them navigate the disappointments that are bound to happen during his or her lifetime?
Here's what I propose:
Acknowledge the disappointment. Is he mad, sad? Validate whatever he's feeling.
Help your child to see and understand that life is full of disappointments. Share a personal experience from your own childhood and explain how you dealt with it. Then help your child come up with a way to cope with the disappointment he is currently experiencing. Coping skills don't just happen, they have to be taught and as a parent it's part of your responsibility to teach them to your child.
Ask your child what she can do to make herself feel better. You may need to offer suggestions the first time around but over time your child will learn what works best for her. Reading a book, doing something physical, painting a picture, etc., are all good ways to redirect disappointment.
Sometimes children are disappointed when they've made a mistake. They may feel like they're not a good baseball player if they strike out or they make feel they're a failure at math if they don't get an A on their test. In these situations it's important to take a close look at why your child feels the need to be perfect. Are you setting too high of an expectation? Do you show your own disappointment when your child doesn't measure up? Sometimes it helps to step back and be more realistic in what you expect from your child.
Once you've helped your child navigate a disappointment you can use what was learned to help her through the next one. You can remind her that she figured out how to deal with it once before and that you know she can do it again.