To plan a birthday party for your son or any child for that matter find out what they like and are in to. Then plan around that. For instance when my youngest turned 5 he asked me "Mommy will you make my cake?" So I asked him what kind of cake he wanted. He wanted an Ice Cream Cake and clueless as to how to make one a friend suggested I look at the one on the Schwan's website. So I did and got the recipe. It turned out wonderful! In prior years with all of my boys I planned their parties according to their age, what they liked at the time, and included them in on the planning. So if its Power Rangers, Marvel Comics, Nickelodeon, or something else find out. Children seem to really enjoy when you get them a cake and decoration with matching invitations of something they like,being asked where they want to have their party, being asked who they want to invite, and just being included in the planning all around. Then let them hand out the invites or mail them. Doing this makes it more personal to them and more enjoyable for them. Once you find out where they want to have it do your homework and find out if it would be cheaper for you to pay for the party package or buy the stuff and just take everyone to the place. For example if it is Chuck E Cheese they want to go to it is probably cheaper to buy all the party supplies, cake and what not then just invite everyone to meet you there. After that is taken care of plan activities based on the child's interest. For example they may be an older boy and in to skate parks and such so plan around that. To save money shop at your local Dollar Tree, Dollar General, Family Dollar, Wal-Mart, K-Mart, and Grocery Store for the decorations and cake. Look for decoration bundles that include invitations, plates, utensils, napkins, table cloths, etc. Buy disposable cameras and let the children document the party from their point of view (this is always a fun idea even for adults). As with any party utilize the web and look for fun and new ideas for cakes, drinks, decorating, etc. Just remember you don't have to spend alot of money to plan and have a GREAT Birthday memory for your son at any age.