Age 1: Invite only family members and close frends only because this birthday is more for the parents than for the child. At age 1, a child doesn't understand the concept of a birthday party. He or she is getting a lot of attention which is all a 1 year old wants or understands anyway. You should not go overboard on presents because too much could scare or confuse a child. You should consider getting specialty items such as a plate that says First Birthday, a 1 year old candle and possibly a table cover that everyone could sign with fabric paint to have as keepsakes that can someday be shown or given to your grown child.
Age 2: 2 year olds should have one or two playmates over for a small birthday play day. Again I suggest you keep a birthday plate and other keepsakes for you 2 year old.
Age 3: 3 year olds should have three to four playmates over, and at this age you might try a birthday game such as who can stack the blocks the highest. I do not reccomend having a clown or playing any games that require a blindfold over a child's eyes due to the fact either can scare children at this age. Remember that your child has just turned 3, and the playmates are around that age too. They are still not able to understand fullly structured games very well. They only know if they do something good or better than other children, everyone will give them attention. Again I suggest you collect keepsakes.
Age 4: At 4, children should now be ready for a "real party". I suggest four or five playmates. 4 year olds friends are ready now for party decorations. Games such as musical chairs and carrying a hard boiled egg on a spoon to the finish line without dropping it relay race can be appropriate. But remember that games will be played and finished much sooner than you think. Consider having a few of your child's favorite videos on hand. Even if the kids have seen them 100 times, they will enjoy them. After an hour or so, you will probably need a break and the children might be cranky. A movie they are all spellbound by will be a great way to relax the kids and you. You might want to consider spreading a couple of blankets on the floor and have some pillows handy for sleepyheads.
Age 5: 5 year olds should have a big party, but remind them that this is because they are the "big 5" and a "big" party will not happen every year. I suggest you decide if you want to do it yourself, rent a building or park area but still do it yourself or call a caterer.
Ages 6-9: Birthdays can be overnight parties filled with popcorn, junk food, movies and games. As long as you let the kids stay up all night and sleep in half the next day, this type of party can be super "cool" (they won't make it all night even though they will try). If it's summer time, think about letting them sleep outside in a tent or on a screened in porch (just be sure to let the parents know exactly where their children will be sleeping and you should plan to check in on them a few times during the night).
Age 10: This should be done anout the same as age 5 in terms of it being a special age. Ten is a great age to consider renting a facility such as the local pool, roller or ice skating rink or even a day at the zoo. To save money, check with the place where you plan to hold the party to see if you can decorate, bring in the cake and other party favors instead of buying the supplies from them.
Ages 11-15: Do the same as ages 6-9 with an overnight party.
Age 16: If they even agree to let you have a party, then consider yourself lucky. If they do, then you need to let the teenager decide what kind of party it should be. Remember kids at that age are very into who is popular and who is not. Don't push your child into inviting everyone you might think they should (because they might be afraid of being made fun of for having a party at home with their parents). They know who they can invite and who they can't without fear of peer pressure. My best suggestion for this age is either a pizza party at home ar at a pizza parlor or a pool party, depending on the teenager's interest.