The best advice I can offer is to repeat Elmore Leonard's points 9 and 10 from "Ten Rules for Writing Fiction":
9. Don't go into great detail describing places and things, unless you're Margaret Atwood and can paint scenes with language. You don't want descriptions that bring the action, the flow of the story, to a standstill.
10. Try to leave out the part that readers tend to skip. Think of what you skip reading a novel: thick paragraphs of prose you can see have too many words in them.
Personally, I don't skip anything when I'm reading a novel. Too many years of working as an editor have conditioned me to read every word. (In fact, I'll just confess it: I read every letter of every word. Which makes me a pretty slow reader.)
But I understand what Elmore Leonard is saying about those thick paragraphs that lie dauntingly on the page, the ones you know will leave you (or your reader) gasping for air before you've waded through them and staggered into the life-giving white space at their end. Those dense chunks of verbiage, you simply must pare down.
I'll also refer you to the Leo Tolstoy passage in a wonderful little book, Illuminations: Great Writers on Writing, edited by Christina Davis & Christopher Edgar:
In some French novel he [Tolstoy] had found a description of the smell of roast goose that covered several pages. “It’s quite true,” he said, “that by the time you get to the end you can smell that goose. But that’s not the best way of imprinting things in people’s minds. Do you remember, for example, the way Homer conveys Helen’s beauty? With these simple words: ‘When Helen walked in, at the sight of her beauty old men rose to their feet.’ One pictures the radiance of that beauty right away. No need to describe her eyes, her mouth, her lips. Everyone is left free to imagine Helen in his own way, but everyone is struck by this beauty that draws old men to their feet at the mere sight of it.”
--From Illuminations: Great Writers on Writing, edited by Christina Davis & Christopher Edgar (T&W Books)
There are, of course, exceptions to every rule. Some writers can weave long and beautifully descriptive passages that succeed brilliantly. Most of us, however, would do well to follow the advice of Homer, Tolstoy, and Leonard.
Just below Elmore Leonard's advice ("Ten Rules for Writing Fiction") we find this from Diana Athill:
2. Cut (perhaps that should be CUT): only by having no inessential words can every essential word be made to count.
That's what all writers should ultimately strive for: to have only the essential words. That would be perfection (which is unreachable, but it's a good thing to aspire to).