Set your financial goal. Calculate average gift then multiply the average projected number of gifts received. Solicit donations pre-campaign. It is always good to insure success by obtaining large gifts before the campaign begins. Food - heavy hors devoirs are great for your callers.
Board members are happy to provide treats for the volunteers.
Goodie bags simple give away items, i.e. Mugs, pens, calendars, etc make great expressions of thanks for your callers. Give these to each caller toward the close of the evening. Media be sure to publicize in whatever media is available about your preparation for the phone campaign. Some people have sent postcards to their call lists prior to the event to alert them to the reason the money is being raised. Decorations are not necessary but may add to the festive ambience of the event.