To get this achievement you need to collect the 38 items (mostly notes from Julia) scattered throughout the game in various levels. If you follow the collectible guide then you should get this achievement through natural progression. The youtube video below is for ONLY the 38 items that you need to find.
*Note: the video provided is not mine and credited to Redemption Mode and his entire collectible guide can be found here
http://www.xboxachievements.com/forum/showthread.php?t=57876....