So, story points are used to judge the complexity and difficulty of a story in relation to other stories, right? Well, I've seen story pointing sessions where the stories all tend to be the same points (13 or so) or the story points are so controversial that a 1/2 point is added to one story and not another.
Here's a trick. After a few sprints, create a spreadsheet of story references, their points, and the sprint in which they were played. Sort the spreadsheet by point, sprint, then reference. Next time you go to a story pointing session hand out the list to the entire team and use this as a reference when someone trys to split hairs with a story. The point of the matter is to keep pointing consistent among the stories, not highly precise.
As time goes on, the team can strip stories from the spreadsheet that no longer seem like good representatives of that size.
This technique works great!