The first is to better understand oneself -- all the unconscious biases and prejudices that we carry around, the psychological mechanisms that cloud our judgment and decision-making, and the stone-age legacy that shapes our social life.
The second step is to better understand the people around us who have a different culture, racial background, sexual orientation, religious belief, or who we consider "different" in some other way. Ironically, the trick at this stage isn't learning more about their differences, but about all the ways they are just like us.
The third step should be the easiest, but it requires the most discipline. It consists of refusing to go along with the common practice of otherizing people who are different.
At the most basic level, that means objecting when someone tells a sexist or racist joke, not out of some sense of political correctness, but because it perpetuates a culture of "us" and "them." It's literally de-meaning because it robs some people of their individuality.
Political and social labeling is akin to the same thing. Think about it, do you know anyone who is consistently and completely "left" or "right" on every issue? Does it make sense to apply those labels so freely?
Being OtherWise doesn't mean papering over disagreements. But it does mean being able to disagree with people without demonizing them. As psychologist Jonathan Haidt told PBS' Bill Moyers, we should make questioning people's motives, intelligence, or patriotism as inappropriate as smoking in public. Not only should we avoid doing it ourselves, but we should call each other on it.
In the midst of the political campaigns, that's going to be really tough. But if we can't do it, steps one and two will be pretty meaningless.