During the race there needs to be some way of keeping runners on the course. The most common approach is a combination of arrows painted in the street and people standing by pointing the runners in the right direction. Make sure in advance they know the right direction. The more corners you have the more people you will need. There is a special paint called athletic athletic field marking paint which is not permanent, and sprays out top of the can in a wide stripe instead of the side like a normal spray can. You will find that spraying from a regular spay can onto the road can be difficult and since the paint is permanent, cities don't like it. It is also nice to have a person on a bicycle lead the race, this way the lead runners do not take the wrong course. The most difficult job as race director will be finding volunteers and committee chairs that will oversee specific aspects of your race. Most runners like volunteers at one-mile intervals reading split times.