Frustration usually results when things don't go as expected.  Creating a proper expectation of the process and then steering the client through the various milestones, can often go a long way towards ensuring a positive experience and outcome.  When issues arise (as they always do), maintaining good and open communication between all parties is vital to righting the ship.  Recognizing the pitfalls, and understanding what may or may not be a reasonable resolution, allows us to navigate successfully through most any challenge likely to be encountered.