I've given up trying to cut perfectly. No matter what technique I use, it's always a little off. I've learned to live with it and not stress out anymore. I make quilts to use, not to enter into shows, so fantastic precision really isn't needed. But I do need for things to line up. So I make little corrections here and there along the way. I found that I don't like working with starched fabric. I love the feel of the fabric unstarched and that's part of the pleasure of quilting that I don't want to give up. I do find that using a ruler with simple fine lines works best for me. The rulers with fat yellow marks is too hard to line up. I admire your efforts to improve your quilting skills! You will learn along the way what works best for you.