Objective: Learn the handful of stitch patterns and sewing habits that produce clean, durable, saleable seams on the Janome MC6650.
For nearly every beginner home-business item—tote bags, pillow covers, pouches, napkins—you only need three stitches, all built into the MC6650. The straight stitch (pattern 1) joins two pieces of fabric; set length to 2.5mm for general sewing. The zigzag (pattern 2) stretches and finishes raw edges so they don't fray; a width of 3.5mm and length of 2mm is a reliable default. The three-step zigzag is best on knits and for flat edge finishing because it lies flatter. Beyond stitch choice, four habits separate hobby work from sellable work. First, always backstitch (press the reverse button) two or three stitches at the start and end of a seam so it won't unravel after washing. Second, keep a consistent seam allowance—most patterns assume 1/4" (6mm) or 5/8" (16mm); line the fabric edge up with the engraved guide lines on the needle plate rather than eyeing it. Third, sew a quick test swatch on a scrap of the actual fabric to check tension (top and bottom threads should lock in the middle, not loop on either side) before touching your real piece. Fourth, finish every raw edge inside the item with a zigzag or the machine's overcast stitch so the seam survives repeated use—customers notice fraying. The MC6650's automatic thread tension and needle-up/down button make these habits easy: set needle-down so fabric doesn't shift when you pivot at corners.
Example: Suppose you're making a cotton zippered pouch. On a scrap of the same cotton, sew a straight-stitch test line: length 2.5mm, and check the swatch—if the top thread lies flat and bottom thread shows no loops, tension is good. Now seam the pouch sides: line the fabric edge against the 6mm (1/4") plate guide, press reverse to backstitch 3 stitches, release and sew forward the full seam, then backstitch 3 stitches at the end. Switch to zigzag (width 3.5mm, length 2mm) and run it along the raw seam edges to overcast them. The result is a straight, locked, fray-proof seam ready for sale.
Try it: Take two 10cm scraps of a woven cotton. Sew them together with a straight stitch at a 6mm seam allowance, backstitching at both ends. Then finish the two raw edges of your seam allowance with a zigzag stitch. Inspect the back: the straight seam should not pull apart when tugged, and the zigzagged edges should show no loose threads lifting away.