I took a class in rotary cutting...learned a lot about cutting properly...like using the markings on the ruler not on the mat. In fact, she made us turn our mats over to the blank side. The quarter inch seam must be gauged by the thread, needle, foot of your machine. Figure out where that is and mark it or something. Pressing can cause things to be wacky. Place the iron down on the fabric...don't rub it on the fabric. Use starch. (I prewash and starch fabric before I even cut on it.) I found that true-ing up my block sections as I went help tremendously. When making HST's I always cut my blocks 1/2 in larger than the finished size of my blocks....5 in for finished 4 1/2 blocks. True them up using the diagonal marking on the ruler. They make squaring up rules as well to assist if you wish to purchase one. All that being said....it takes lots of experience to be great at it!!