I am low on agreeableness with people at my place of work...I am interested in knowing what you have learned about how to get along with co-workers and overcome low Agreeableness. I think that people who are not naturally gifted in an area are often best suited to teach it because they have had to really understand it and work at it.
Let me offer three tips.
1. Separate ideas from people. At a meeting, instead of saying "I like Joan's idea" or "I dislike Fred's idea," say, "I like the idea of doing X" or "I dislike the idea of doing Y."
Even when it is obvious whose idea it is, talking about the idea in impersonal terms helps to defuse a lot of the emotion that goes with it. Surprisingly, even when you agree with someone's idea, they often feel more comfortable if you express that agreement impersonally.
2. Express yourself gently. In fact, "I like" or "I dislike" is often too strong. Better to list pros and cons.
Instead of saying, "Writing our new Web application in COBOL would be insane," say, "one concern with writing the Web application in COBOL might be...."
Remember that the stronger the basis for your position, the less emphatic you have to be in stating your case.
3. When you encounter personal criticism, take it as constructive. If you cannot find a way to see it as constructive, ask a friend to help you find a constructive aspect to it.