I would like some tips for debugging WCF Web Service exceptions

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <s:Fault>
      <faultcode
            xmlns:a="http://schemas.microsoft.com/ws/2005/05/addressing/none">
            a:ActionNotSupported
      </faultcode>
      <faultstring xml:lang="en-GB">
            The message with Action '' cannot be processed at the receiver,
            due to a ContractFilter mismatch at the EndpointDispatcher.
            This may be because of either a contract mismatch (mismatched
            Actions between sender and receiver) or a binding/security
            mismatch between the sender and the receiver. Check that sender
            and receiver have the same contract and the same binding
            (including security requirements, e.g. Message, Transport, None).
      </faultstring>
    </s:Fault>
  </s:Body>
</s:Envelope>