Source: Martha Stewart
Cut a length of ribbon (ours were 1/2 inch by 18 inches, 5/8 inch by 22 inches, 1 inch by 32 inches). Holding 1 end of ribbon in left hand, between index finger and thumb, with remainder of ribbon pointing at a 45-degree angle toward index finger's tip, wrap ribbon over and around index finger, creating an X-shaped loop.
Slide out finger, holding loop securely. Tuck opposite end of ribbon through loop, pulling to create a flat knot.
Repeat 5 times, adjusting each new knot so its bottom left touches the bottom right of the previous. Trim ribbon ends, leaving 1/4 to 1/2 inch at each side.
Tuck each ribbon end into knot at opposite end to complete star, pulling gently to adjust; use a dab of glue to secure.