Have a large bottle of aspirin ready. Everyone will have to delivery at the same time but no one will show up on time and you will always have 100 errands to run but have to wait. Use the yellow pages, both on and off the Web. You can rent tents, tables, chairs, lights, grills, etc. You should also plan to have your carpets cleaned a day or two after to prevent setting of dirt and stains.
Wicker baskets work great at holding napkins and plastic utensils on a table.
Try using smaller sizes for utensils so they can stand on end and be easier to retrieve when juggling a paper plate. You can find great buys on them at garage sales and with a little imagination and a quick visit to the local crafts store you can decorate them to match any theme. They'll also be welcome door prizes for after the food has been served or give them to all the helpers who stood by you to put this event together. Large public events will usually require a number of permits. This means the zoning department, the health department, the recreation department, and on and on.