Try to help a person who is suffering, but keep a little distance for yourself.
Understand that you can't solve everyone's problems. The other person usually just wants to know that you understand and care.
If you find yourself becoming overwhelmed by someone's emotions, temporarily switch your attention to something else -- tackle a home project or play with your kids.
Keep in mind that reacting in some degree to others is good.
When your feelings are confused, step back and ask yourself, "How much of this is them and how much is me; what's my role?"