Ever notice that fresh asparagus can be a little woody? It's hard to know exactly where to cut each stalk. If you cut too far up, you're wasting precious, delicious, usable asparagus, but if you cut too far down you are likely to find a nice bite of too much fiber in your dish, then later in your napkin. To avoid the problem of not knowing where to cut, just snap the son of a gun! Take the root side in one hand and the tip side in the other (midway down the stalk), and snap downwards, as you would when preparing fresh beans. The breaking point will be where the woody part ends and the tender part begins.
Also, if you're using frozen asparagus in a recipe that calls for it to be cut into pieces, cut it while it's frozen. That way it stays firm and doesn't smush apart when you bring the knife down on it. You can also snap it into pieces of a desired length using your hands while it's frozen.