this was the case for me too when i first started rag quilting. i only make rag quilts, and the more you make, along the way you will discover little tips and tricks. when i sew my blocks into rows, then go to sew my rows together, i always start by matching up my first seam. then match up the seams after that. don't worry about the edges because you will sew a line of stitching around the whole outside of the quilt edge and then that will get clipped and rag, so you won't see it. i hope that makes sense, if not, please send me a message. i'll be glad to help!
