I used to have the same problem, but with practice you can make it a lot better. What I found helped, was finding something to describe, it can be anything, and then maybe spend five minutes brainstorming ways to describe it, and then write a paragraph of description. I also find planning can help, but I generally don't plan all that much when writing (though I should), at least not what I'm writing at the moment. I'm the most unorganized person though xD
So yeah, plan and practice. That's really all the advice I can give you. OH, and if you want to make it stand out, make up your own metaphors, don't just use ones that have already been used, because people are bored of them and they're predictable.
Good luck!
Hannah ♥