An interesting experiment is to try to say something nice to or about someone every day for a month. Try it. It makes us much more aware of what we say and why. It encourages us to change our perspective so that we notice others' good qualities. Doing so also improves our relationships tremendously.
A few years ago, I gave this as a homework assignment at a Dharma class, encouraging people to try to praise even someone they didn't like very much. The next week I asked the students how they did. One man said that the first day he had to make something up in order to speak positively to a fellow colleague. But after that, the man was so much nicer to him that it was easy to see his good qualities and speak about them!
--from Taming the Mind by Thubten Chodron, published by Snow Lion Publications