Too loose a stitch can make the finished work look sloppy. Keeping the garment tight in a hoop is another highly recommended tip, especially when working with sweatshirts. The basting threads remain in the canvas only until the stitching gets started. The basting is removed as you approach it. KarenS8888 says recommends stitching from bottom to top or top to bottom, left to right or right to left, or stitching from the center out.
Experimentation is the best indicator for how many strands of floss to use on any given project.
Bejoyce notes to take care not to pierce the threads of the canvas while stitching. That can make removing the threads later extremely difficult. TBalodis reminds us that when stitching on waste canvas, you are stitching over the corners of the warp and weft rather than stitching over the squares on aida. Vfindersis recommends stitching with dampened floss. Pulling the waste canvas out from the finished stitching can be the most difficult and tedious part of working with this medium.