The League of Women Voters has a website http://www.vote411.org/which can help you make sure you got to the correct location to have your vote count. Also make sure you know when your polls close so you don't arrive even a minute late.
Note that if you are in line to vote before the polls close you still have the legal right to vote. Right now the lines are generally the shortest they will be all day.
Besides making a difference in the outcome of this specific election your decision to vote in this election makes you visible to your representatives as they consider how their votes in the next 2/4/6 years will influence your vote as they try to get reelected.