The goal of this step is to end up with twenty-one 12" squares of background fabric.
I fold the yardage selvage to selvage, and then fold again, so it fits nicely on the ironing board which doubles as a longer cutting table. Then I roughly measure out 13(ish) inches, using my handy-dandy ruler.
Then I cut with scissors.
I repeat until I have 8 - 13" x WOF strips. I only need 7, but I like to have an extra.
Now I square the strips up and cut into 12" squares. Pretty basic.
I cut them width-wise first, getting three 12"x 13"(ish) squares from each strip.
Then I stack the three, turn and trim the other two sides. Then I repeat for the rest of the strips.
Viola, a stack of 12" squares.