When piecing I do not pin a lot. When petting roew together I pin at cornerd and line up seam lines first. I also start by putting a pin around the corner of the beginning of the seam, that seems to help keep everything straighter. the rest I pin sieways(at right angles to seam). If fabric is slippery orif difficult sea i pin parrel to seam. My machine can sew next to pin till it reaches head.
bottom linedo whatever works for the occassion