Ditto on the gauge recommendation. I own both metal and plastic crochet hooks and both work great. Hobby Lobby puts all crochet hooks and knitting needles on for half price every three months or so. If you have one of those, you can pick up a set in a range of sizes for super-cheap. They also have a 40% off coupon every other week (which is almost as cheap).
Being able to do a single crochet edging, etc. can come in really handy with your knitting.