Heat usually kills the flavor of fresh herbs so try to add it to the end of the dish when cooking or on top as a garnish. Remember that casserole dish? Add a pop of green on top to make your dish more appetizing.
Wash herbs right before using and pat dry with a paper towel. Keep herbs in the fridge by wrapping them in a loose paper towel and storing them in a ziplock bag filled with air. Try to use before 5 days or they will lose flavor.