Date: 10/3/2008 4:06 pm EDT
I'm also planning a pattern with 12x12 and 6x6 tiles. I found it helpful to draw out my pattern on graph paper scaled to the size of the room. It'll make an instant reference when I'm laying out the tile. I did buy some extra tile for scrap and replacement, but with the drawing I could count how many tiles of each type it should take.