Experienced-to-new contributor ratio
Before running an editing event, one of the more important questions you should ask is: Do you or your expected attendees have sufficient experience working with Wikimedia projects to support newcomers during the event? And are there enough collaborators to share the work needed to support the size of the event?
Though anyone can edit Wikipedia and other Wikimedia projects, each project and each language version of the projects have different cultures and practices. If you have some experience or training in contributing to the project, and feel comfortable guiding new editors through the process, you will likely have a successful event.
Most events that train new contributors, need sufficient experienced contributors on-hand to help guide them through questions. Community experience suggests organizers need at least one experienced contributor for every 5-10 expected new contributors. This allows experienced contributors to answer questions, and support new editors throughout the event.