It's a good idea to have a well-scheduled party with activities and games that will keep kids occupied. Plan active games for the beginning of the party and quiet games to help the kids calm down before their parents come to pick them up. Schedule enough activities to keep the kids entertained so they don't run amok. Younger kids may enjoy bobbing for apples or playing pin the stem on the pumpkin. You can mix up games with crafty activities, like making Halloween masks or decorating trick or treat bags.
Scavenger hunts keep older kids focused and occupied. And don't forget the old gross-out box that always keeps kids laughing. Fill some boxes with things like spaghetti for intestines, ketchup for blood and peeled grapes for eyeballs. Blindfold players and have them stick their hands in the box and guess what's inside. Spooky music helps rev up the anticipation.
Goodie bags are a must for kids' parties, but you don't have to blow the budget. A trip to the dollar store in October will yield plastic spiders and other fun Halloween props that make great bagged party favors. If you're going to include food, don't forget that parents appreciate sugar-free snacks.