Get local (even some online) vendors to donate items, and have a raffle.  Really push the raffle, it's good revenue for your club, and some people come out just for the raffle.

have some open flying time, and some games.  Games can include spot landing, limbo, climb and glide, etc.

serve lunch for a nominal fee

make sure you have the amenities available, such as porta-potties if necessary, you don't want your guest to be uncomfortable.

put out fliers around town, and at local hobby shops.