There's a primary election in New York and a number of other states today. I'm on my way to vote in mine, and I encourage you to do the same. It'll give you practice moving the lever, touching the screen, punching the chads, whatever you need to do. Then you'll be ready in November.
I'd also recommend that you plan now to take Election Day off. (It's November 4th this year.) That way you'll be able to help those who need it get to the polls. Can't take a vacation day? Get up early, or go home late. Exercising your right to vote is a privilege and a responsibility; helping others vote is a good deed and will make a huge difference to your candidate.
And don't kid yourself: every vote will count (remember Florida in 2000?), and the election will depend on who can turn more voters out. If everyone who's planning to vote for Obama gets just one other person outside his or her family to go to the polls, he will win.
Not sure who to vote for today? I bet your local paper has endorsements. Mine does. I don't know most of my candidates, but I've met Nora Anderson, and I like her.