Outside of intellect, training, an ability to stage your story and write believable characters and good dialogue, there is another tool that you need:
Imagination and hard work
There is a website that helps with the imagination part: oneword.com. As for the hard work, you will still have to look to yourself for that.
Upon logging into the site, you are prompted to write for one minute about a single word at the top of the screen. This pushes your mind into neutral, allowing your words to flow freely. By limiting your ramblings to a single minute, it forces your sub-conscious to react to the word. You don't have enough time to formulate something cohesive, but your sub-conscious does. You might think this is useless, but some of my best writing has come from these sub-conscious expeditions. Your ability to write will improve, even if what you write on this site doesn't.
I highly recommend a spending a few minutes a day limbering your mind. Your writing will improve and your readers will appreciate it :)