I came across this video today by Paul Boag that effectively defines a method for creating positive relationships between designer and client. It's quite inspiring because Boag pulls no punches in laying out the traditional client/designer issues, but provides some really great advice for keeping projects on track and making clients happy. 

Check it out at: http://events.carsonified.com/fowd/2008/newyork/videos/paul-boag

Reference Links
www.boagworld.com