Don't discuss unpleasant subjects: other people's faults in worldly matters (such as physical or mental disabilities) or their faults in spiritual matters (violations of ordination, for instance). Talk cheerfully about pleasant topics in a gentle and friendly manner.
From The Great Path of Awakening : An Easily Accessible Introduction for Ordinary People by Jamgon Kongtrul, translated by Ken McLeod. Copyright 1993 by Ken McLeod.
Published by arrangement with Shambhala Publications, Inc., Boston.
This site provides an on-line database of commentaries on the Tibetan Buddhist meditation practices of lojong (Mind Training) and tonglen.