- Don't charge a cover. This suggestion is related to the free food and beverages theory.
- Don't do a charity event. If you think that adding a charity element to the event will enhance the appeal, think again. (The exception, of course, is when the whole purpose of the event is charity.)
- Don't make the guest list private. People are generally what make the event. If you make the guest list private, you're effectively making it so that people don't know if the event will be any good.
- Don't hype. By hyping I mean sending a lot of reminders or including language like "everyone is going to be there!" When you hype an event too much, you're either implying that the event isn't all that appealing on its own merits or that the people you're inviting aren't special.
You can usually recruit a handful of people to help supply food and beverages and let everyone else freeload.