Choosing an appropriate site is important. If you plan on playing sports, be sure the location has the proper layout and terrain. If children will be attending, be sure to choose someplace safe and easily monitored by sight. For a romantic date, choose someplace beautifully inspirational, perhaps under a huge tree, along a lake shore, or near the crashing waves of a beach. The type of event should help you in your menu planning as well.
Casual events deserve casual foods - salads, sandwiches, grilled hamburgers, etc.
Romance deserves a little food flair, but even this doesn't have to be difficult. Choose fine quality cheeses, wine, bread and fruit. A sharp knife Seal-able plastic bags Bottle opener, Swiss army knife or corkscrew Food poisoning is often a concern for picnickers. The Mayo Health Oasis has a great list of Food Safety Tips for Picnics . I've found a few sites on the Web that may help you with your picnic meal planning.