Using the Double crochet bind off gives a nice elastic edge to your knitting.
Use a crochet hook that is equivalent in size to your knitting needles. Insert hook knit-wise into first stitch. Wrap the yarn around the hook as if to knit. Pull the yarn through the stitch, moving it off the needle (basically just knit the stitch, using the crochet hook as your working needle). *Repeat for the next stitch. You now have two loops on the hook. Wrap the yarn around the hook and pull the yarn through both loops. You now have one loop on the hook. Repeat from *.