How to Hold the Yarn and Crochet Hook
There are no hard and fast rules about the best way to hold the hook and yarn. Choose whichever way you find the most comfortable. Some people prefer the "pencil grip". The hook is held in the right hand as if holding a pencil.
Some people prefer using the "knife grip". The hook is held in the right hand as if holding a dinner knife ready to cut.
To maintain the slight tension in the yarn necessary for easy, even stitches, you may find it helpful to wrap the yarn around the fingers of the hand opposite the one holding the hook. Try one of these ways, or find another way that feels comfortable to you.
In the illustration below, the left hand holds your crochet work and at the same time controls the tension of the yarn. The left-hand middle finger is used to manipulate the yarn, while the index finger and thumb hold on to the work.
Some people find it more comfortable to manipulate the yarn with the index finger and hold the project with their thumb and middle finger. While you're learning, if one ways feels awkward, try another way until you find the one that suits you.