My numbering for the sections:
Foundation piece the sections. Trim to ¼" seam allowance all the way around.
I prefer to iron the freezer paper foundation onto the side strips too. This way they don't distort when I sew them onto the block and I can get the seam allowances accurate. I also leave ½" seam allowance along the outside edges so I can trim the block to exactly 5" when I'm done.
Make the three center sections. To make the seams line up, I always sew about ½" of seam at the seam intersections first and then sew the rest of the seam from the ends towards the middle. This avoids a lot of slippage of fabric, and I only have a teenie bit of unpicking to do if the seams don't line up.
Attach the three center pieces to each other to form the center square.
Attach the edge rectangles log cabin style to complete the block. Not perfect, but better finished than perfect, right?