The Flatrate module allows the administrator to create different shipping methods for different situations. Each one has a base rate which is the starting shipping price for any order, and a product rate which is charged for each item on the order. Either or both rates may be 0. Each method's product rate may be overridden by specific products for even more flexibility. A Flatrate fieldset is added to the product edit form.
It is generally recommended to set up the Workflow-ng configurations so that only one flatrate method is available for any particular order. For example, your store may offer free shipping for orders over $100. This means that the normal shipping method should check that the order is less than that, and the free shipping method should check that orders are at or over $100. An exception to this rule would be for shipping methods that signify extra service, like expedited shipping or hand delivery.