There are 62 total medals, so you are going to need 31 medals in your Trophy Cabinet for this one.
There are many different ways to come up with 31 medals, but most will come just by playing through the game and competing in the Talent Shows. The Saturday talent shows have a completely unique set of medals. However you can only get 5 per week, unless you go offline and manipulate the Date/Time settings in the System Settings and make every day Saturday. Oh, if only I could do that in real life!
The medal status can be checked at any time to see what you're missing from the smart phone menu. That can get tedious because you have to open up every drawer and figure out what your missing. Here is a list of all the awards: http://www.xbox360achievements.org/forum/showthread.php?t=30
I take no credit for the list. Credit goes to Scrapdaddy. (Thanks).