When I did a rail fence quilt (Queen size), I used 3 fabrics (I believe it was a yard each). I think it looks really nice when there is an odd number of fabrics. I cut 2 1/2 inch strips across the width of the fabrics.
I sewed the 3 strips together. I repeated that sequence until all strips were done. I believe the key is whatever the height measurement is of the 3 strips that are together, cut that same measurement for the width. This way you have a square.
Once you have all those squares, playaround with the arrangement by laying the blocks on the floor or a big table. Once I liked the way it looked, I starting assembly line sewing. It goes really fast doing it like that.
Once I finished the quilt top, there were enough squares left to make to pillows!
I hope this helps.