Know Your "Why"
I partner with churches across the country for all sorts of events. One critical factor for creating a successful event is defining what success looks like. It sounds obvious, but I've discovered that it's often overlooked. I can't tell you how many times an event organizer is unable to articulate what they want to get out of their event. (And it's a lot harder for me to help them make their event a success if they can't or won't communicate what "success" looks like.)
It's easy to think the "why" is obvious, but it rarely is. An event could have any number of purposes. Different churches can do the same type of event of any number of different reasons.
For example, this time of year many churches hold a Trunk or Treat, Fall Festival, or similar Halloween related event. Some are doing it as an evangelistic outreach. Others are doing it to build bridges with community members. Still others want to provide a Christian alternative for their families. Others may have completely different purposes. Although the events may be superficially similar, different choices will be required to accomplish different goals.
As a college professor of mine used to say, "If you can't explain it, you don't understand it." It's crucial to know and be able to communicate the desired outcome for your event. If nothing else, taking tome to clarify the purpose in your mind will help you make better decisions.
It's much easier to recruit and retain volunteers when you communicate why what their participation matters. Volunteers can do a better job when they understand what the desired outcome is. Shared purpose increases commitment and effectiveness.
Clearly defined outcomes allow you to measure the effectiveness of your event. This will enable you to make it better next time, or maybe decide it's not working and it's time to try something else.