When you’re learning to crochet, hold the yarn very loosely, so that you can pull the loops through easily. A fairly loose tension is fine, and you could also use a slightly smaller hook to make it easier to push the hook through the fabric.
Once you finish a crocheted piece, always sew in the ends of the yarn carefully and thoroughly to prevent all your hard work from unravelling.
When you first start crocheting, it’s really important that you learn how to hold your hook and yarn correctly, to avoid getting RSI or aching joints.

