Modern Art 5
Unlock 150 Dog Tag displays
Dog Tags are similar to CoD: MW2/BO playercards. You'll have 3 sections to unlock certain Tags and each one requires you to do different things! So some require you to simply win a match on a gametype, where as others require you to get the most kills in a game.
None of them have any descriptions, so its pot luck when you unlock them. You'll also want to grab the Dog Tags from the downed enemies you've killed. You'll need to have a total of 150 displayed for the achievement to unlock.
Waiting on a full list of how to obtain each one.
You may have seen this, but it's a pretty good list of medals/dogtags:
While boosting/earning level 50 for "Crysis, What Crysis" however, you'll more than likely earn enough unlocks to clear the "Mystery" panel of dogtags, along with an assortment of the "Awards" getting you VERY close to the 150.