Practice makes perfect.
Practice speaking and listening – and use technology to analyze your skills and measure the progress.
Sounds sophisticated? Not at all.
All you need is a simple speech recorder or just your smartphone. Make it a habit to record all substantial conversations that you have during the day, then allocate ample time to listen to the recordings and do a conscious “flight debriefing.”
You will be amazed.
That happens pretty much to everybody because you have never heard yourself “from the outside.” You will notice some obvious mistakes or mannerisms that sound so … well, disgusting, that you will not need much effort to get rid of them (like talking too much, interrupting, using pleonasms, periphrasis, discourse markers, grandiloquence, or being excessively magniloquent – just like I am now).
Additional benefit: you will retain much more from the conversations. That’s a good thing, especially when the discussion is important, and you have no chance to make notes. Next time you’ll impress your counterparts with your attention to detail.
One caveat though. You have to be discrete, i.e. your recording device must be hidden. Obviously, when you start openly recording the conversations all the participants do not talk naturally (yourself including) or do not talk at all. Another thing to bear in mind: this may be illegal in some states…
(Originally answered on Quora)