I'm of the opinion that you shouldn't 'practice' fmq on a top you like. I would go with straight diagonal lines. You can connect the lines from the center of the paisley square that was created when the blocks were joined to the notch in the cross. Do this in both directions. Then it looks like if you sew a straight line on the side of this square, the line would extend to hit the notch again. See if there are other diagonal lines you can do based on the blocks. Great top, love the colors!