This is a skill that can be learned in school. In fact, you will almost never see it in the real world, so I recommend taking a few classes in case you're one of the vast majority of lemmings who has never written or spoken a coherent sentence. It will be years before you truly grasp what you're doing, but you can fake it until then.
Communication requires you to 1) know what you're trying to say, 2) organize your thoughts to maximize the impact of how you say it, and 3) know your audience to maximize their retention of what you have to say. Like when Peggy Hill wants to get Hank's attention, she mentions propane.
Rule 1: Communication is your responsibility. You are the one with something to say, and no one else, frankly, gives a rat's hind end about it. If you want to be heard, you must make your presentation clear and compelling.
Rule 2: Have a plan. Think before you speak or write. I seriously do not have the time to listen to you stammer and mutter around whatever point you have.*
Rule 3: Keep it brief. No one is going to wade through four dense paragraphs of anything to get the point at the last sentence. NO ONE. You don't do, so don't do it.
As a writer, this stuff is kind of basic for me, but it is a total freaking mystery to most of the world, who seem to believe all they have to do to communicate is open their mouths and let whatever unedited nonsense passing through their white matter at the time pour out. That may work for the significant other who just wants to get to the fun stuff, but it does not work on anyone else, so stop it.
Communication is hard work. People today are generally dumb as a bag of hammers and shallow as a rain puddle in Arizona. They aren't used to thinking at all, so you have to think for them in what you communicate. The proof is how easily lemmings believe anything they hear on TV. They're like that chick who knows they can't put anything on the Internet that isn't true. A news reporter can't possibly lie. He's a reporter.
Which leads to the caveat. There is great power in communicating well. People do tend to believe something written down, no matter how ridiculous, just because someone took the time to write it down without emoticons and punctuate it. If you are one of those communicative people, you can quickly rise to a position of authority over lemmings. Use your power wisely, because to those whom much is given, much is required (Luke 12:48), teachers will be judged more harshly (James 3:1), and causing little ones to stumble leads to serious consequences (Matt 18:6 and Mark 9:42).
Push button. Receive bacon.
*This attitude absolutely does not fly in the work world. You must practice patience in your dealings with the everyday, whether customers, co-workers or bosses. We'll cover that later.