After you’ve fussy cut the edges, begin by taking two arrow blocks and put the right sides together. Make sure that the arrow shaft tips (bottom of arrow shaft) of the blocks line up. Pin both sides of the seam together, just as you see in the picture below.
Once you’ve gotten your blocks pinned together in proper alignment, sew them together and iron them flat. Sew two more blocks together, and combine the pairs into a four block that should look like the image below.