I collected some tips about effective talking and listening from videos [1][2], readings [3][4], and a workshop I attended at UCI [5].

I- Best practices (from Julian Treasure [1])

A. Four virtues of speakers: honesty (be clear and straight), authenticity (be yourself), integrity (be your word), and love (wish them well).

B. Eight tools for talking: register, timbre, prosody, pace, pitch, and volume.

C. Seven sins of talking: gossip, judging, negativity, complaining, excuses, lying, and dogmatism.

II – Warm-up your voice and body

Usually involves making sounds with lips, tongue, throat, chest, arms, etc. It also involves relaxing your body. Search for videos in YouTube, there are many.

III- Posture

Your posture talks about you. Being conscious of our posture while speaking helps us to be understood and to understand others [4]. Our brain changes by the way the stand [2][3].

References:
[1] http://www.juliantreasure.com/

[2] http://www.ted.com/speakers/amy_cuddy

[3] Dana R. Carney, Amy J.C. Cuddy, and Andy J. Yap, Power Posing: Brief Nonverbal Displays Affect Neuroendocrine Levels and Risk Tolerance, in Psychological Science, Sage, 2010, DOI: 10.1177/0956797610383437
Available at: link

[4] Pierre Weil and Roland Tompakow, Notre corps parle : Le Langage silencieux de la communication non verbale, Courrier du Livre (September 5, 1989)

[5] Effective Communication Workshop at UCI (link)