Write sentences that are as concise as possible. Each sentence should communicate one idea. When you include too much information in a sentence, your writing apper to be rushed and sloppy and your readers will lose interest.
Place all essential information in each sentence so that your readers do not become confused. In its composition guidelines, the University of North Carolina at Chapel Hill give this example: "Having finished with studying, the pizza was quickly eaten." This could mean--although it's unlikely--that the pizza had been studying. Instead, write: "Having finished with studying, the students quickly ate the pizza."
Write using accurate and precise words to convey your meaning. In a scientific article, for instance, you would not write "add some acid." Instead, you would specify which acid and precisely how much of it was needed. Likewise, in fiction and non-fiction writing, avoid such generic words as "nice." Use a dictionary or thesaurus to pinpoint the word you need, such as "generous," "friendly," or "considerate." This makes your descriptions stand out in the reader's mind.
Delete unnecessary words. Many writers use two words when one will suffice. For example, rather than describing the weather as "wet and rainy," just say '"rainy." This has more impact because it's more specific, and it stops your work from seeming over-written. Using several adjectives when one will do ("the huge big man") or unnecessary adverbs ("he shouted loudly") makes a writer seem indecisive and weakens the prose.
Remove clichés from your writing. These make your work appear to be lazy and unoriginal. Readers will be unimpressed. Instead of using such stock phrases as "he was as tall as a mountain," think about what information that you want to convey and create an original construction that's relevant to your story. You could write, for example, "he was as tall as the cherry tree that grew outside his bedroom window."