Have a clear idea of the program purpose. The program committee should be large enough to handle the necessary tasks so that no one person feels too overburdened. Call on other committees for support depending on the type of program.
Publicity is a key ingredient.
Have experienced people be responsible for publicity, and determine media contacts and deadlines. Set up a realistic timetable so that all concerned have a clear expectation of the time involved. Evaluate each event afterward. If your audience evaluations are good, don't be discouraged if a program doesn't draw the numbers you expect. Often, unforeseen events can change the attendance at a program.