Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Gameday Guru (50 points): Complete a head to head match on Xbox LIVE.
Drawing Some Plays in the Dirt (10 points): Create at least 10 custom plays.
Gold Miner (10 points): Find 90+ Potential Training Camp Invite.
Media Darling (10 points): Get your approval level with the media to 80, after one season.
Mr Popularity (10 points): Get your approval level with the fans to 80, after one season.
Teachers Pet (10 points): Get your approval level with your owner to 80, after one season.
Man of the People (10 points): Get your approval level with your team's players to 80, after one season.
One Big Happy Family (10 points): Get your approval level with your coaching staff to 80.
Xs and Os Guy (20 points): Create at least 25 custom plays.
Goal Oriented (15 points): Accomplish all of your Season Goals.
I'm The Decider (10 points): Get 100 percent correct defining moments during a game day.
Best of all Time (100 points): Go undefeated during a season.
We Like You (25 points): Get an overall Approval Rating of 85, after one season.
You Arrived (30 points): Win your first Super Bowl ring.
We Love You (50 points): Get an overall Approval Rating of 90, after one season.
One for the Mantle (50 points): Win the Coach of the Year award, after one season.
Welcome to the Club (125 points): Win 100 games with a created coach.
Repeat Offender (100 points): Win back to back Super Bowls with one team.
We Idolize You (75 points): Get an overall Approval Rating of 95, after one season.
Best Ever (250 points): Win the Super Bowl 3 times with the same team.

Additionally, there are two secret achievements, both of which are currently unknown:

Secret achievement (10 points): Unknown.
Secret achievement (20 points): Unknown.