Sampler quilts
 

I would like to make a sampler quilt, queen size with 12" blocks. How do I go about figuring how much fabric I need? I would like it in three colors, a dark, light and medium.

Really hard to answer. What size are you making? Queen is a general term because we don't know how much you want to hang over the edge. 3"? 14"? do you want extra at the top for a pillow tuck? Also, a sampler has many different blocks, each one taking a different amount of each fabric.
http://www.quilterscache.com/StartQu...iltingtwo.html