I tried to answer earlier, but accidentally closed the browser window.
The first thing is to keep the conversations positive and free of negative emotions. The object is to get them to think and force them to justify their positions without using catch phrases and talking points.
Be sure to keep the discussion focused to one subject. They will try and change the subject when forced to think about it. They will try and dismiss your viewpoint. Be prepared to provide logical arguements and facts to support your opinion. Use historical and respected information sources. Force them to do the same. That makes them use their brain to do the research. Once you get them to think and reason out their ideas, exposure to other points of view help to keep that process going. Try to get them to read more and turn off the TV.
They also have to understand how that TV, RW radio,and all the other same sided voices constiitute a form of psychological manipulation. Get them to watch Outfoxed, read George Lakoff, get their news from many sources.
resources:
http://www.skepticsannotatedbible.com/www.liberalslikechrist.org
www.thomhartmann.com
www.airamericaradio.com
www.whiterosesociety.com