The German twisted cast-on is an excellent technique for casting on stitches on an edge that requires some stretchiness, for example, around the neck for a top-down sweater, around the head for a hat, around the leg for cuff-down socks. This technique is a stretchier version of the long-tail cast-on.
You will need:
Working yarn
Working needles
Video: how to knit the German Twisted Cast-On
Photo tutorial: how to knit the German Twisted Cast-On
Preparation step: make a slip knot, leaving a long tail of yarn, and place it on the needle.
Step 1: hold the yarn in a slingshot position, with the long tail looping around the thumb and the working yarn around the pointing finger, holding both strands of yarn with your other fingers.
Step 2: place the needle above the work, close to your body, and pass it under both strands of yarn wrapped around your thumb.
Step 3: with your needle, catch the thumb strand that is farther away from you and bring it under the other thumb strand, forming a small loop on the needle.
Step 4: catch the finger strand by passing the needle above it and then below…
…and pass the strand through the loop on the needle.
Step 5: drop the yarn from your thumb and tighten the stitch by pulling on the strand with your thumb, replacing your hand in the slingshot position.
Repeat Steps 1-5 until you have casted on the desired number of stitches.