I used to have a hard time matching up the blocks but I am OK now for the following reasons - I match all the seams with a pin sticking it straight thru and do the same with the corners( do not bend the pin and pushback thru the fabric like normal just leave them sticking straight thru until you pin horozontally then you can remove them) and then I pin horizontally thru the line on the paper making sure it matching the line on the other piece - sorta like what you do when hand piecing. If there are a lot of matching seams I baste first all those seams and make sure they match. Then I sew the block together slowly pulling the pens out - you do not need a lot of pens. It is a lot more work but it beats trying to tear out all those little stitches.