John Sides of the always interesting blog, The Monkey Cage, has some useful advice on how to watch the remaining weeks of the presidential and congressional campaigns: pay less attention to the advertising and the polls and more to the "ground game" of the various parties and candidates. He says that political science research has demonstrated that that can make a big difference in outcomes. He also notes that what happens locally in House and Senate races is also more susceptible to get out the vote efforts.
What we can't tell, however, is how newly enacted voter ID and related laws will limit turnout of otherwise qualified voters. I fear that may be a sleeper in the eventual results.