I have a client who only writes occasionally. He sends me his copy, I edit it for his odious spelling, his oddly placed use of capitalized letters, fix what seems awkward and then I send it back. His latest piece was humorous, as usual, but there was something not quite right. I called him on the phone to ask him why the change? He said he was taking a writing course and was trying to sound more like a “real” writer. Then I asked him about the funny incident and as he described the whole scene to me, I wrote it down. I typed that all up and sent it to him. He called back to say that he was blown away at the difference and how cool the article now sounded. He asked what I did. I told him, nothing special, I simply wrote it how you told it. That makes it “real”.
Unless you are writing for a technical reason such as medical reports or legal notes, there is no need to be stiff and formal in your writing. If you are relating a day-to-day story, use every day vernacular. For characters, it’s okay to develop their ‘personality’ and give them certain speech patterns. For the most part, just write down what you would say if you were speaking the story. If you really want more descriptive writing, try improving your vocabulary, use more flowery speech and then write that way!