Just my thoughts:
1. Mental toughness. That's really what Indiana sports teams have lacked since the '87 Hoosiers. (That, and a real, burning desire to win - but I've got no doubt the Colts have that). If they end up struggling out of the gate, get behind, throw some interceptions, give up a big play, have a miracle bounce go New England's way, Vinatieri misses a chip shot, Peyton's under lots of pressure, etc. will they have the mental toughness not to let it get to them and keep playing their game? That's the key because past playoffs Peyton & Co. have gotten rattled when things didn't go well. Regardless of what the pundits might say, the onus is clearly on the Colts here. The Patriots have nothing to prove. They are merely playing for ring #4. The Colts are the ones with the monkey on their back, the QB that couldn't win the big one, etc. I was very pleased to see that the defense held up well in Baltimore, even when everything wasn't going perfect.
This is the one huge difference in the team this year that makes me think they've got a chance. The D stepped it up when they had to and the team found a way to win with Peyton struggling in the playoffs. I believe that can do wonders for Peyton's confidence and the team's overall poise.
2. Get off to a good start. Of course it is always better if you don't need to tap into the mental toughness reserve. If the Colts start out with a good defensive stand, a nice drive, and get the lead, things will be much better. Though never count Brady and the Pats out.
3. Score 29 or more points. The Colts D has long been suspect, but it is usually their offense that flames out in the playoffs. How many of those playoff losses were 34-33? There's no reason that an offense with this many weapons shouldn't be able to put up four touchdowns in a game. Add an extra point on top for safety. If the offense scores 21 points or less, I think that puts a lot of pressure on the D.
4. Be ready for the new wrinkle - and be ready with one of your own. One thing that Pittsburgh amply showed the Colts last year is that the good teams save something for the playoffs. As brichard once put it, Bill Cowher has the play he's saving for the second half of third playoff game. The Colts usually show you everything they have in the regular season. It should come as no surprise other teams are ready for it. It doesn't have to be a trick play, but some new wrinkles, both before and after halftime, would be most welcome.
Those are some items I have off the top of my head. Of course it would help if the defense played well again this week too, but that's obvious. You always want the defense to play well.