When using fresh herbs to make a bouquet garni, exact measurements are not that critical - trust your instinct. Bruise the herbs slightly just before adding your dish to release more flavours.
When using dried herbs:
We prefer to use fresh herbs, but dried herbs are just as successful. Use 1 heaped tablespoon dried parsley, 1 teaspoon dried thyme (we prefer a level tablespoon lemon thyme), 1 teaspoon dried rosemary and a single dried bay leaf. Tie up the dried herbs in a small bag sewn of muslin. Or grind the parsley, thyme and rosemary and add to the dish. Add the bay leaf, lemon peel, and celery stalk whole and remove before serving.