Harry Enten says there are five polling lessons we should take from the 2012 election season:
1. When likely and registered voter polls disagree in high turnout elections, you should usually go with the registered voter surveys.
2. Cellphones are generally needed for an accurate telephone poll.
3. Internet polling is the wave of the future.
4. Internal polls published publicly generally should not be trusted.
5. When state and national polls disagree, you should generally go with the state data.