Set realistic expectations.
In a quiet moment, jot down three goals you want to achieve with this celebration. If it's your parents' 50th wedding anniversary, for instance, you may want the party to serve as a family reunion of sorts as well as a way to honor your parents' marriage. Or your dearest wish for your daughter's wedding may be to launch her into a happy marriage as well as celebrate her new independence. Bring your list to your next Money Group meeting and get input from other members. They'll make sure you're being realistic and truthful. (No, it probably isn't a good idea to throw your husband a surprise 50th birthday party just because your sister and your best friend did the same thing for their husbands.) When you have clear, meaningful goals in mind, it makes it easier to avoid overspending on over-the-top but often meaningless extras.
Make a budget.
Use my party planning tool to itemize each and every expense, including space, food, drinks, flowers and incidentals like personalized paper napkins. Seeing how everything works together will help you avoid a common party planning mistake—spending too much on one area, like food or an open bar, and not having enough left over for other expenses. After you've totaled up everything, go ahead and add another 10 percent buffer for last-minute cost hikes and unforeseen expenses.
Find ways to cut back.
If you're like most people, adding up the various expenses of a big party can give you a severe case of sticker shock. That's when it's time for you and members of your Money Group to look for some creative cost cutting. Some ideas: Skip the sit-down dinner and host an extended cocktail party with passed hors d'oeuvres instead. Or, in addition to wine and beer, offer a signature cocktail instead of a full bar. Cutting the guest list by just a few names can shave hundreds off the final tab. Together, you and your group can brainstorm other great ideas.