Can't say how to boost it, but to get it legitimately, I did it by building the best team I could with Short Pass and Man Defense chemistry. Use the auction house to look for the cheapest guys that upgrade your spots AND have SP or MD chemistry. Make sure all your players are in the right spots (having people out of position- even a LT in a RT spot- causes a huge drop in awareness). I suggest having five WRs and five CBs in your roster, even though only three of each are on the lineup screen. Also, decent backups in the LE/RE, LOLB/ROLB, MLB, and DT positions.
When you play offense, play ball control. Short passes, runs if you can get positive yardage. Wear out the clock by selecting plays rather than doing hurry up. You want your offense on the field, not theirs. Don't be tempted to throw deep because you'll be intercepted way too often. Smart route in or out routes when it's 3rd down, and try to only throw to players that are actually open. Use your total control passing- lead slants and drags upfield to get those extra couple yards when they are open.
When you play defense, go to play type, Man Zone. I generally use 3 plays- all three have the two blue circles. I use the one with 4 down linemen (the squares at the bottom with the red arrows) and two linebackers (the circles in the middle) for plays that they have 2RB, The one with 4 linemen and 1 linebacker for plays that they have 1RB, and the one with 3 linemen, 5 defensive backs, and the linebacker in QB spy for 5 wide... and I usually tell that linebacker to blitz if the guy I'm playing isn't running a mobile quarterback. Once you've called these three plays, you can just go to recent plays to make it easier.
Inside the red zone, I'll usually audible to a blitz.... but make sure all five of their receivers are covered in man coverage. A lot of blitzes leave the RB or FB open.
Adjustments- if your opponent plays a lot of screen passes, hot route your DEs to QB contain. It will generally blow those up. It'll also help with those scrambling QBs, though not so much with the option players. You shouldn't have *too* much trouble with hot route TEs on streaks since you should have a DB on him instead of a LB (that's why I go with LB=RB rather than CB=WR in play selection). For option players, I suggest bringing in an extra blitzer and committing to the RB with the left trigger before the play. Hopefully that will mean your DE takes the RB and the blitzer (a safety, likely) will get the QB. I haven't quite figured this one out though.
Generally, this caused a lot of games where I'd get an interception early and score on my first possession, sometimes leaving me up 14-0 in the first quarter... and a lot of people quit at that point. I wound up going 11-2 at the Pro level 2 rank on the 360 version- first round bye and Super Bowl winner. I actually finished less than half these games because so many people quit. Of course... it won't work against the "really good" players who know how to maximize their offense and defensive schemes.... but it does work against the general public.