Wrapping the yarn over your crochet hook, called a yarn over (abbreviated yo), is the most basic step to every stitch in crocheting. Yarn overs can be used before or after you insert the hook into the next stitch, and sometimes you yarn over two or more times, depending on the stitch.
Yarning over is very simple, but you have to do it right or you won’t be able to draw the yarn smoothly through the stitch.
1- Make a slip knot.
2- Slide the slip knot onto the shaft of your hook.
3- With your yarn hand, hold the tail of the slip knot between your thumb and middle finger.
4- Using the forefinger on your yarn hand, bring the yarn up behind the hook.
5- Lay the yarn over the shaft, positioned between the slip knot and the throat of the hook.
If you try to wrap the yarn over your hook from front to back, instead of from back to front, crocheting is more difficult and you end up with twisted, tangled stitches.