Provisional Cast-On with a crochet hook
A provisional cast-on is a handy trick to know when hand knitting. The idea is that the stitches that you cast on are held on waste yarn. You can then work your piece of knitting, knowing that your stitches are safe. When ready, you can peel away the waste yarn and have lovely row of live stitches to work with. This allows you to knit away in the opposite direction without having the need of grafting or seaming. Or, it can form the basis for a more complex cast-on such as the tubular cast-on. Once you know this technique, you'll find many place to use it.