I like my add a quarter ruler. But I could do it without it also.
hevemi told us about freezer paper piecing. You can use ordinary paper, also. You can make up to 20 blocks with the same piece of paper, and never have to rip off any paper. It's called Paperless Paper Piecing, and is very simple. When you fold the paper back on the stitching line, just keep it there and sew on that line against the edge of the paper. Then you can cut off your seam allowance with the ruler or not, and go ahead and fold the next seam back, put on the new fabric and sew against the edge of the paper. We had a demo of this at our September quilt club meeting, and I was quite fascinated by it.