One of the best ways to elevate a book -- no matter what the genre -- from merely good to truly great is to sniff out stale images and replace them with fresh ones.
Recently, for instance, I've been immersed in the work of Andrew Taylor, a British writer with several series of mystery novels. The one I'm reading now, The Lydmouth Series, has all of the usual elements: a world-weary but brilliant detective inspector, a love interest in the form of a nosy journalist escaping a bad love affair, quirky secondary characters, and a tiny English village where more people die per year than in all of New York City.
There are many British series competing for space in this particular lane, but Taylor's language elevates his books above most others. Take a look at these two examples from The Mortal Sickness:
First one gaitered leg emerged, then another; next came the rest of the archdeacon -- a thin man whose dark clothes accentuated the greenish pallor of his face. His grey hair was cut very short, like a convict's stubble.
The kettle, which was large, squat, and blackened, sat sullenly on the range and obstinately refused to produce any steam.
Now, aside from the sly humor here, what do you notice? Look at that description of the archdeacon: Taylor is comparing him to a criminal, which is apt, given the corruption in the church. And that kettle, which we would expect to be round and cheery, is instead squat and blackened and sullen, like an angry animal -- which of course suits the mood of that particular scene. Taylor is, in effect, employing opposites to freshen up these descriptions, and these vivid, unique images add another layer of complexity to a novel that is already a fast-paced, fascinating mystery.
Here's one more example from An Air That Kills:
He returned to the desk and stared down at the glazed bowl (of crocuses), which had been painted a shade of white that reminded him of the tiling in public urinals.
My God. Taylor gets away with comparing a pot of spring flowers to a toilet bowl! This is another use of opposites to create a surprising image. What's more, this is a fantastic choice because the man who received those flowers didn't especially want them (he won them in a raffle), so he gives them to his wife. She also doesn't want them (she already had bought some). She, in turn, gives them to the woman who will become her husband's mistress, who doesn't want them either, because those flowers represent something she can't have (domestic life with her lover). So what does she do? She smashes that pot of flowers, a.k.a. the urinal, to the floor. So funny, so apt, and such sleight of hand that you barely notice it until you really think about that image.
Language like this is enough to make any reader sit up and take notice. So, as you're revising your novel, take note of the stale phrases and replace them with fresh ones to give the book a new jolt of energy. Let yourself play on the page and be as outlandish as possible in your choices. A lot of the images won't work, but many will. You won't know until you try them. Now go have some fun!