If available, organically-grown herbs are best, and they usually aren't too much more expensive than their conventional counterparts. You can also grow herb plants on your windowsill or out in your garden.
I find washing the grit and sand of leafy herbs to be a bit annoying, so I usually do it as soon as I purchase or harvest the herbs so they are ready for recipes when I need them. This technique works best for basil, mint, parsley, and cilantro. Hardier herbs like rosemary and thyme should be washed just before using so they don't mold when stored in the fridge.
To clean the herbs, separate the bunch and compost any leaves or stems that have brown spots or have wilted. Then, fill a bowl with clean water and dunk the herbs in a handful at a time. Shake the herbs around a little so the sand and dirt sink to the bottom of the bowl. Lift the clean herbs out of the water, shake off, and dry in a salad spinner or with kitchen towels.
Different herbs require different storing techniques because of the tenderness of the leaves.
Once the cubes are frozen, you can store the herbs in plastic bags and defrost to use in soups, stews, smoothies and other dishes.
What are your favorite tips for buying, cleaning, and storing fresh herbs?