Plenty of great advice here 

"13. Speak of yourself but little. Your friends will find out your virtues without forcing you to tell them, and you may feel confident that it is equally unnecessary to expose your faults yourself.

14. If you submit to flattery, you must also submit to the imputation of folly and self-conceit.

15. In speaking of your friends, do not compare them, one with another. Speak of the merits of each one, but do not try to heighten the virtues of one by contrasting them with the vices of another."

13:  Faults and virtues speak for themselves?

I believe that. You don't?

Yes, and my question mark reveals a fault.

Calumniate is my new favorite word.

So much good:

16. Avoid, in conversation all subjects which can injure the absent. A gentleman will never calumniate or listen to calumny.

17. The wittiest man becomes tedious and ill-bred when he endeavors to engross entirely the attention of the company in which he should take a more modest part.

18. Avoid set phrases, and use quotations but rarely. They sometimes make a very piquant addition to conversation, but when they become a constant habit, they are exceedingly tedious, and in bad taste.

19. Avoid pedantry; it is a mark, not of intelligence, but stupidity.

20. Speak your own language correctly; at the same time do not be too great a stickler for formal correctness of phrases.

21. Never notice it if others make mistakes in language. To notice by word or look such errors in those around you is excessively ill-bred.

...and I need to look up what the word "calumniate" means...

I can't say that I follow these rules, but I will consider doing so....  at least a little bit more....