Accuracy is very important because the person you are writing to does not, in all probability, know you, nor is he/she likely to be familiar with the circumstances which caused you to write. Therefore, be as specific as possible, giving all the pertinent information as accurately as you can.
For instance, if you are complaining about a product you have acquired that is bit faulty, include the main facts such as where you bought it, the date you bought it, the model number of the product, if it has one.
Bear in mind, much of today’s institutional business is run by the number. So, be accurate in the facts and figures (especially in business writing) and remember, nothing is as bad for your writing as wrong facts.
You can take it for granted that the person you are writing to does not have time to wade through a long paper. If he receives a piece of correspondence that runs more than a page, or at most, two, he will probably end up slipping it in the folder with the hope that he will look at it later -when he has time.
Can you afford that?
Would you want your readers to treat your writing like this, especially when you are a professional writer?
So, try to address the purpose of your writing at the start of piece, post, news, letter, or whatever it is.
Keep your paragraphs short. Frequent paragraphing breaks up the harsh solid look of writing, and even if it isn’t easy to understand, the indentations make it look easier, and give the reader energy to go on.