- Hooks- well duh. I suggest (at least) one of each in sizes from D to at least K, so that you'll be prepared for any project you want to tackle.
- Yarn needle - big and blunt, usually plastic. This makes weaving in yarn ends much easier.
- Stitch markers - for some projects with shaping or colorwork, you may need to mark your place. There are tons of kinds of stitch markers out there to use, from handmade bling to plastic rings. You don't have to be fancy or expensive with these (I use paper clips, myself).
- Yarn snippers - I keep around both a small pair of scissors and one of the Clover yarn cutter pendants. If you do a lot of travel crafting, the second will come in very handy.
- Tape measure - doesn't have to be fancy or excessively long. Helpful for swatching and checking length of projects like socks.
See, it's a short list! Short but full of very useful things. Happy Crocheting!