One thing that especially caught the attention of the players was my portrayal of the halflings. It really brought out the character of the little runts, and made the encounters memorable and fun.
So what did I do? I sat on the floor when portraying halflings. Sound stupid? I don't care, it worked like a charm. We have a low table, so only my head and shoulders were seen by the players, which reinforced the effect of them talking to a halfling.
And I didn't have to use the silly voices!