Do not use Calculated shipping -- this will seriously reduce your conversion rate because shoppers need to be logged in to see the actual shipping cost. 

Instead, eBay and Zentail recommend creating one policy that incorporates Free Standard Shipping (no need to select a carrier / service level) and Flat Rate Expedited (again, no need to select a carrier / service level). This policy should be used on an account-wide basis. For items in your catalog that require an alternate Shipping policy, you can implement an override at the SKU level according to the instructions in the Related reading section below.

Related reading: