WashingWash your herbs in the garden before you bring them in. Spray them down with the hose, and allow them to dry first. Then cut them. That way she you won't wash away any of that fresh flavor when you cut them.
If you are wanting to dry your herbs, put them in a pillowcase. Take them outside, and swing the pillow case around in the air. It really works. And you get a little exercise in the process.
Use a sharp knife when you cut your herbs. A blunt knife can bruise your herbs. Bruised herbs oxidize quicker. This leads to discoloration. If you're using a food processor, make sure the blades are nice and sharp.
Choose the right cooking and chopping technique for the dish you are making. Rustic dishes do better with chopped herbs. The flavors are yielded more slowly, which adds a more homey feel to the food. Finely chopped herbs blend easier with other ingredients, but loose their flavor more quickly.
So put these tips to use, and let me know which one works best for you.