Write with your reader in mind. You want to keep things simple: no over the top flowery sentences that belong in poetry not in a novel, no run on sentences that are a paragraph long, or clumsy writing that is hard to understand. When you write this way, you are making your reader aware.
Aware of what you might ask? Your writing. You don’t want your reader cognizant of the fact that they are reading a book. You want them focused on the story to the point that they are walking beside the characters and experiencing their every move.
You want them to continue reading until the end accepting every coincidence and slightly questionable storyline written. We often refer to this as the suspension of disbelief. If the reader is focused on the story and not the writing, they will accept most of what you throw at them without stopping to question its plausibility.
Remember: Clumsy writing that’s hard to understand makes readers aware. Don’t let the words get in the way of a great story.