Use two colors to track the ends
The square knot, also called a reef knot, is made from two half-knots in opposite directions. Here red starts on the right and green on the left. The same color goes over in both half-knots because that end changes sides after the first crossing. This is a useful gift-cord exercise; do not use the knot for lifting, climbing or other critical loads.
Follow the same colored end
These original sketches show the sequence and color changes. Follow the colored cord through each tuck before tightening.
If the finish twists
If the two halves twist instead of lying flat, undo the second half and check which colored end you crossed over. Repeating “right over left” from your current viewpoint twice makes a different structure. Tracking one cord by color is easier while you learn.
Smooth both halves before tightening hard. On a small gift, the final knot should sit where you can see it, rather than hiding under a bow or squeezing against a sharp corner.
Use the lesson thoughtfully
A square knot is a general cord skill, not proof that an ornament is a traditional Chinese knot. Pair it with a simple handmade tassel and a personal message. For the visual composition of a card, try the ornament designer.