If the venue is a green park or on a private property you should be faced up to the risk and you should conduct risk assessments on all aspects of your event.

A risk assessment is a methodical process plan, which enables a hazard to be identified, the risk that harm will occur. The extent of harm is to be evaluated with a suitable way to avoid the harm by such hazard.

Also make sure your venue is suitable for the event. Questions you may ask yourself:

Is it big enough? Is there enough capacity for people to circulate in case of fire? Can everyone park without trouble? Is the egress good enough?