There are two things to do to minimize the likelihood of having problems voting:
Rule 1) Bring a cell phone to the polls, and make sure it's fully charged. That way, you can call any of the voter-support hotlines right away if need be. Don't rely on a friend or a pay phone, because of Rule 2:
Rule 2) Don't leave the polling place until you are certain your ballot has been cast properly, and that it's for the people you intended to vote for.
If you run into trouble anywhere in Maine, call the Maine Civil Liberties Union at 207.774.5444 anytime during voting hours on Election Day. They have free help and legal advice available.
Also, Monday's Wall Street Journal has some other advice, too.