I see a lot of writing coming over the transom from people who seem smitten by metaphorical imagery. Unless you can write it like Flaubert, I recommend finding another way to depict whatever it is you are trying to describe. The metaphors and similes I see usually don’t work that well. When you start using these figures of speech, it’s easy to fall into cliché. (I advise writers to “avoid metaphorical imagery and clichés like the plague.”) Editors and agents tend to view this kind of writing as characteristic of the novice and a sign of the writer’s insecurity. Like you’re trying too hard. You don’t have to model yourself after Ernest Hemingway or Raymond Carver. But still… to paraphrase Freud, sometimes the best way to describe a green tree is to just call it a green tree.