I square my blocks, then I try to keep the seams matched when I start making rows and then when again when I start sewing rows together I match seams to keep them as even as possible. Now, my daughter's quilt she had put her rows together and they were so uneven that we put sashing between the rows so that we didn't have to match up so much. She's a beginner. Her next quilt is so much better. Practice will be on your side.