Last year my birthday boy asked for either a Zombie party or a Pirate party. A four-year-old Zombie party may have raised a few eyebrows, so we went with Pirates. It was a super fun one to do! There are so many things you can do on your own with this theme, stay on a budget, and still have it looking good. Most of the kids in attendance were aged three to eight, and they were all entertained fairly equally.
So hang on. It's a rather long post, but hopefully will give you some ideas on what (or what NOT) to do. I've organized this post into sections: Invitations, Activities, Games, Food, Cake, Favors, and Decorations.