As we used to say in Chicago, vote early and vote often. While it's true that the United States, despite all our bloviating, isn't actually a democracy (you'd have to go to Costa Rica for one of those) it still requires a certain amount of participation on your part.
So get out there and do your thing. Unless, you know, you're a Republican. Then you're welcome to stay home and drink yourself in to a stupor. In fact, I'd prefer that you do.