I recommend freezing rather than drying cilantro so it will retain more of its distinctive flavor. To freeze, wash and drain whole sprigs, then pat dry with paper towels. Place a few sprigs at a time into small plastic freezer bags and freeze.
Or chop cilantro and freeze in ice cube trays. Place a tablespoon in each section, cover with water and freeze. That way, you can easily add just the right amount to your favorite recipe.
If you do decide to try drying cilantro, tie bunches at the stem ends and hang them upside down, away from direct sunlight. Both frozen and dried cilantro are best used in cooked dishes, not salads or salsas.
When you buy fresh cilantro at your grocery store, look for bunches with fresh leaves and avoid those with wilted or discolored foliage.
To keep cilantro fresh, place the bunch, stem side down, in a glass with an inch or so of water. Cover with a plastic bag, secure with a rubber band and store in the refrigerator. The cilantro should stay fresh for up to 1 week if you change the water every other day.