Stitch markers also are useful to keep your project from unraveling when you take a break. Just slip one onto your working loop after removing the crochet hook before setting the project aside.
Also, be sure to get stitch markers that are intended for crochet, not for knitting, because you have to be able to open them, like a safety pin. A crochet stitch marker is placed directly into a loop or stitch once it has been made. In a pinch, you can use a hoop earring or a wine glass marker, but avoid using a real safety pin because the yarn can get caught and snagged in the spring coil. I like using "lobster claw" stitch markers with charms because they stay closed until you want to open them, they have smooth edges, and look pretty!