Crochet hooks are not specifically for right or left handed people, either one can use them. Since everyone crochets a little differently, the way of holding a crochet hook is up to personal preference. There are two basic styles:
The "Pencil" Grip: Holding the crochet hook like you would hold a pencil.
The "Knife" Grip: Holding the crochet hook in an overhand grip, like you would hold a knife.
Either one is fine. Switching back and forth between the two may help from having your hands get tired. Remember! Crocheting should be relaxing. The tighter you hold the yarn and hook, the harder it will be to work. :)