Keep it simple.
At all ages, simple events tend to be successful and more fun. Complicated parties usually require extensive planning with little additional fun-value. What's most important to the kids? Friends, goodies and gifts!
Watch your numbers.
To keep things under control, the number of guests should be equal to one to one-and-a-half times your child's age. (A four-year-old would have 4 to 6 guests, an eight-year-old can handle 8 to 12 guests.) For a sleepover party, divide that number in half. (Multiply the number of guests times three to determine the number of vacation days you'll need to recover from the event!)
Involve the guest of honor.
Involve your child in the planning and set up. Your child will be happier with the results and you'll be forced to delegate some of the responsibility! Keep in mind that in case of a disagreement, YOU are the ultimate decision maker for the event.
Create a schedule of events.
Things will go more smoothly if you have a planned schedule. If you know that cake-eating should be done by 2:00 you can move things along if the kids are dawdling. The schedule will keep you more calm.
Discuss the details of the event with your child a day or two before the party. Talk about what behavior you expect from your child. Review appropriate manners regarding arrival of guests, games and activities and opening of gifts. When you clearly describe your expectations, you can avoid the behavior problems that arise when a child is brimming with the excitement of the party environment.
Handle misbehavior wisely.
Despite the best preparation, many kids become overly stimulated at their own party. You may find your usually well-behaved child jumping on your new sofa. If this happens, calmly take your child to a private corner. Acknowledge that you understand today's excitement. Then, clearly identify two things: what you don't want your child to do, and more importantly, what you DO want done instead.
Pick your battles.
Relax your regular rules a bit. This isn't a good time to insist that your child clean his plate before dessert.
Know WHY they misbehave.
If you understand why some of your little guests are acting "goofy" you can keep the proper perspective. First, the excitement of the event can wind kids up. Second, some kids get jealous of the guest of honor. Third, some are just acting normally, but it doesn't match up to your idea of proper behavior.
Calmly correct bad behavior.
If you see something you don't like, take the child aside and make a specific request for change. Be polite, but clear and firm. "We don't climb on our furniture. Please stay off the table."
Re-direct their energy.
Distract a misbehaving child by giving him a task to do, such as passing out the cake or assembling parts of a game. A busy child is less likely to be disruptive.
End on a good note.
Lots of parties fall apart at the very end, when the planned activities are complete, but parents have not yet arrived. Have a quiet fill-in ready, such as coloring, bead-art, or even a video movie.