Let your guests know the atmosphere of your upcoming party by picking a specific theme. Not only does this make the guest comfortable in knowing what to expect when they arrive, it helps build their anticipation and creative with costumes before the big event. Throwing a little devils party for the kids? Send out pitch-forked party announcements. Perhaps it's a time to go a bit "batty?" Let that kooky theme come out in your invitation! Is it a masquerade affair that includes masks, dancing and wine for the adults? Guests will appreciate knowing up front.
The more specifics you can provide, the better: date, time, place, RSVP information and required attire (come in costume, bring a pumpkin for carving, etc.).
If you plan on holding a costume contest, a sure hit for the little ones, be sure to put it on the card, lest that surprise ends up being part of your bag of party tricks.