General

A gentleman should strive to uplift the feelings and moods of those about him.  For this reason, he should work to keep his own attitude positive, and to remember to only converse in positive terms with those around him.  As one speaker said, telling others about your woes probably can't help you, and certainly can't help them.  Therefore, there is no reason to discuss problems in public.  These are things that should stay within your own barriers, and should be reserved for discussion with only the most intimate of friends.

What not to discuss

The world does not want to hear about your bodily functions, your illnesses (unless you're asked specifically and can tell us that you're doing better,) your IRS audit, or how you told somebody off at the grocery store yesterday.  People will act interested in these things, but if you pay careful attention, they will make all effort to get away from you as quickly as possible, and to stay away as long as possible.

What to discuss

Tell us about your kids, but do it in a way that could not be considered bragging.  Tell us about the exciting trip you took to wherever you took it.  Tell us an exciting story about your parents.  Talk to people about the happiest times that you can recall.  They will get wrapped up in your excitement about those times, and will subconsciously decide that you are an enthusiastic magnetic person.  They will be enthralled with your charisma, and want to spend more time with you as they can.