A little of this goes a long way, so use caution. There is such a thing as a conversational tone, but writing is not talking, nor is it conversation. Writing is more formal and it's meant to last. It's like putting ideas in a carbonite word-freezer to save them for all time; timeless prose, and all that. Writing entirely the way you talk quickly tires the reader, unless that writer is Garrison Keillor. If you are Garrison Keillor, I don't suppose you'd care to make a guest post on my blog?
That said, every writer has had the experience of typing along with everything moving forward in that magical, Goldilocks at the third chair, don't get any better than this sort of way. And then, all of a sudden, like a problem out of a Chinese algebra book, along comes an idea they don't know how to explain. I mean, the writer knows what they want to say in their head, but the words on the page don't do justice to what they mean. In fact, upon review, the words look like the writer just took a big swig of stupid-juice and dropped their IQ by 25 points. Then, paralysis sets in and the concept stands out like a cold sore on a prom date, in all of its pink, scabby-wet glory.
It's times like these when the writer needs to take a step back and ask themselves, "How would I explain this to my 13-year-old cousin?" Why the 13-year-old cousin? Good question. The average American reads somewhere between an 7th and 10th grade level. Let that regurgitate for a while. The average cop, nurse, homeless guy, burger-flipper, office manager, convenience mart checker-outer, and anyone else you are likely to encounter, reads as well as the typical middle-school student.
Yes, there are specialized audiences. An article written for a peer-review team of nanotechnology cardiovascular surgeons reading about a new way to do whatever it is they do will probably not need this advice. Then again, such a writer probably isn't reading this essay. Know thy audience.
Something else I am not saying is to dumb the whole thing down. People might not be specialized readers, but most are smarter than they're given credit for being. We're pretty good at spotting a phony, except the really good phonies. They get elected to high office where they can practice their phoniness for years while our tax dollars pay for it. But I digress.
Writers are far more convincing when using words and phrases they understand. Don’t use big words for the sake of using big words. That's like putting a spot of neon-orange lipstick over the cold sore. And that's just wrong. Remember, writing is communicating. Even super-secret journals are a way to communicate. For those troubled areas, where the idea is barely clinging to understandability, just talk it out and write it down. We're all expert talkers and writers need to leverage that ability.