1. Leave early - playoff game & normal Saturday afternoon traffic will make the last hour of your drive at least double. Also, if you are planning to go to Patriots Place instead of tailgating, go REALLY early or you will be shut out of all the restaurants except 5 Guys.
2. Don't park in a stadium lot, unless you have lots of time after the game and plan to do a post-game tailgate. It takes hours to get out, particularly if the game is close and everybody stays until the end.
3. Do park at an outside lot along Rte. 1 facing in the direction you want to go AFTER the game (or park in one that advertises "easy out" or a cop at the entrance that will allow you to take a left to get out). Two that I use (one in each direction):
A) If you are coming down Rte. 1 South towards the Stadium (from Rte. 95) try Lot 33. It is on your right hand side as you approach the stadium. You are getting close when you go through a traffic light at North Street (McDonalds on your right), pass a liquor store lot, then one more lot, then you go over a small bridge - the entrance to Lot 33 is the next driveway after the small bridge. There is a state cop there after the game that lets you make a left onto Rte. 1 north after the game. After the game, Stay in the left-most lane once you get onto Rte. 1 North, even though it is on the "wrong" side of the road - you will fly by all the other folks on the "right" side of the road once you get beyond the North Street intersection. This lot is good as it is very close to Patriots Place and the Hall (about 1/2 mile walk). Cost is $50 per car although sometimes the jack it up $10 for the playoffs.
B) If you are coming up Rte. 1 North (from 495) towards the stadium, right after the state police barracks and the junction of Rte. 140 you will see a Dunkin' Donuts on the right. Immediately after the Dunkin' Donuts & the orange cones they put there to funnel in the Rte. 140 folks, is the Pinebrook Office Park parking lot. It's usually $40 per car and they almost always have lots of spaces. The drawback is that it is just over a mile walk to the stadium from here. However, because it's so far out, again it is an easy left hand turn out (sometimes a cop is there, sometimes not, but there are breaks in the traffic here in the left-most lane) and back to 495 about 2 miles down the road.
Bring lots of stuff for tailgating, including stuff to munch on and drink (non-alcoholic) after the game while you are driving and/or waiting to get out of your lot.
Have fun!!