This is a wonderfully informative talk on how to get people to really listen to what you have to say. I really like the 7 deadly sins of speaking and think they are just great rules to live by in general. They are:
5. Not taking responsibility for yourself
7. Being dogmatic and confusing facts with opinions
I think that just avoiding this DON'T list in your daily life will give you a lot of credibility.
Also, implementing HAIL into your life will make you a happier individual as well as making you the kind of person that people want to listen to.