i think the display has to thought out. eyecatching. try holiday tablecloths. check 2nd hand stores for some.
don't over load your table. if it's too crowded people "think your stuff isn't selling". put out a few of each item. store the rest under the table. pull out if someone in inerested and looks around.
if possisble i like to have christmas music playing very low. just getting people excited-thinking of the holidays.
also do things for kids/students/teachers in school colors. they sell better.