A friend was reading my third draft of a YA Science Fiction novel and pointed out that sometimes he didn't understand my sentences or my world. He explained that some of the adjectives I chose didn't produce the sense of the world I was aiming for. That hit me really hard and then totally clicked.
So Lesson #1 in what I've learned about writing:
The image in a reader's mind is of utmost importance. It is the heart of writing and the reason why so many people write and why so many people read. So that first image in your reader's mind needs to be the focus of your sentences and your paragraphs and eventually your entire book. As writers we don't have the luxury of movie screens where the world and characters are produced for the reader. In fiction, the writers have to do the work for the reader.
And so the image should be the focus of every sentence. Once your image is clearly laid out for your reader then breathe life into it with sound, smell, action, feeling.
Only then will you have produced something worthy of the reader's affection.