- When a friend loses a loved one, don't send sympathy form letters of the variety that a CEO might send to an employee.
When a young person loses an intended life partner, don't say, "well, you're still young," and start pointing out attractive members of the opposite sex.
When a parent loses a child, don't tell him or her that suffering is spiritually rewarding or a sign of God's love.
When someone loses a grandparent, don't assume that it's no big deal because you're not close with your grandparents, or because grandparents are old and are supposed to die, anyway.
Don't talk during Mourner's Kaddish. It may just be another kaddish to you, but people saying Mourner's Kaddish are in mourning, and they deserve consideration while they remember their loved ones.
Don't make assumptions about people's beliefs about God, angels, and the afterlife, and definitely don't try to push your beliefs on those who are in mourning. It's not the time.