How to Make a Slip Knot for Crochet
Make a circle with yarn or thread.
Pull a loop through the circle.
Insert the hook in the loop.
Pull gently and evenly to tighten the loop and slide the knot up to the hook. You want the loop to be able to move easily on the hook but be snug around it. Take care that the loop stays on the wider part of the hook and is not on the thumb rest or the narrow part near the head.