Key People of Influence are good communicators – it goes without saying. They have refined their elevator and social pitches; they know how to talk up their products to prospects, clients and customers; they can create win-win solutions to engage partners. They can write their own profiles, social media statuses, blog posts, articles and books – or can they?

A surprising number of educated, intelligent, savvy entrepreneurs who can talk their way in and out of any business deal turn out to have much less well-honed skills when it comes to written communication.

The main errors that authors who are not professional writers (and even some who are) make, fall into the following categories:

Their sentences or paragraphs are not logical. “Picasso’s art, which is quite possibly the world’s best-known abstract painting, is considered more famous than Van Gogh.” Do you get why this sentence doesn’t make logical sense? The writer didn’t compare like with like; he compared Picasso’s art to Van Gogh the artist. You know what he means to say, but you might well have to go back and re-read the sentence to understand what the author really wants to say. It’s faulty logic in the thinking process that produces sentences like that, or the notice for passengers at Sydney Airport: “Has anyone put anything in your luggage without your knowledge?” Illogical writing also includes giving information in the wrong order, writing sentences which are chronologically messed up and sometimes simply using the wrong word or term

They don’t say what they mean, or mean what they say; their writing is often ambiguous. @David_Cameron tweeted, “It’s unacceptable there’s a loophole allowing paedophile ‘training manuals’, that’s why I want to protect children by making them illegal.” He definitely didn’t mean that he was planning to outlaw children, but that is what he said; just as Paddington Station probably didn’t intend to execute passengers when it stated that “Passengers must stay with their luggage at all times or they will be taken away and destroyed”.

Ambiguity often crops up when writers haven’t taken on board some simple rules of sentence construction that make it clear who or what is being referred to. Other kinds of mistake also make for ambiguous writing, but ambiguity always takes readers away from your message and sometimes causes them to give up on your blog post or book.

They have forgotten, or maybe never knew, the basic conventions of grammar and punctuation that we all unconsciously use to decode the English language into meaningful communication. If your writing doesn’t conform to some classic rules, it often fails to get your vision across to your reader, or simply confuses them.

A sentence starts with capital letters, must contain a subject and a verb, should follow a single train of thought, then end with a full stop (or exclamation or question mark). In between the capital letter and the full stop, other punctuation marks need to be applied accurately to make sense of information being conveyed.

As I was writing this piece, a KPI posted on Facebook, “Jesus was on train back from London. Two old boys with matching Scotland baseball caps, putting the world to rights. They are so loud.” Several people left comments expressing amazement that Jesus had been on the train, that he was with a friend and wearing a baseball cap. What the KPI meant was: “Jesus! Was on train back from London. Two old boys… were so loud.” Doubly confusing was his use of both the past tense (“was on train”) and present tense (“They are so loud”) in reporting what was apparently a single incident. A basic knowledge of classic grammar and punctuation is essential to lucid writing.

Their writing style is convoluted and long-winded. It doesn’t get the writer’s point across in an incisive way. If there’s one thing that divides the amateur from the professional fiction writer, it’s the tautness of their writing style. Amateur writers’ sentences often meander, twist and turn; they use many more words than required; and over-complicate their syntax, sometimes in an effort to sound sophisticated. This can end up confusing and slowing down the person trying to read the article or chapter. Seasoned writers, on the other hand, create crisp, elegant sentences in which every single word is precise and necessary, which have correct grammar and functional punctuation. They will make sure, through several drafts, rewrites and self-edits, that each phrase delivers its message with the fewest and the simplest, though most apposite, words. This makes their writing easy to read and dense with meaning – a fully satisfying experience.

The final fault I often find, in business books especially, is that the author’s writing style is dry and dreary; or full of industry jargon; or pseudo-academic; or too clever by half; or just plain boring. If a writing style is not dynamic and full of the author’s personality, readers lose the will to live, let alone to read to the end.

Bad writing is like a dirty window: you have to keep moving and peering and finding patches of clarity to see the vision that is being presented to you. Lucid writing is like a clean window: the glass is so clear that you don’t even notice it’s there when you are taking in the vision beyond. So whatever you’re writing, whether it’s as short as a tweet or Facebook status, or something as vital as a blog post or your book, make sure your writing is lucid, by checking that it is: