I've always believed that writing fiction can be simplified down to two elements: imagination and translation. You're capability to imagine combined with your proficiency in translating your imagination into words is what ultimately makes a piece of fiction. Yes, there's many, many, MANY sub-elements within these elements, but in a broad view I think it all boils down to those two things. Some people are vivid imaginers -- they can picture every microscopic detail of a scene in their head and can envision these images as simply or complexly as they chose. Some are talented translators -- they write with the perfect blend of words and structure, and can put their thoughts down with ease. The truly gifted writers have both, obviously, but I think there are many writers out there (myself included) who may feel that they lack somewhat in one or the other. Personally, I feel that I translate my imagination better than my imagination imagines. I see this as problematic, because one can certainly get better with the "craft" of writing with some old fashioned hard work. But can one get better at imagining? If so how? (beyond the obvious which is reading a lot).
That's really the only way to do it. Maybe not ONLY reading, but perhaps watching TV/movies. In addition to that... just experiencing life. I've found that a lot of inspiration for stories I've written have come from real experience, or a book I've read or a show I've seen. I actually think TV can be good inspiration for coming up with plot ideas. For example, I like writing mystery stories... and I'll see an episode of a show where the killer was able to kill his victim with a knife attached to a long string wrapped around an exercise bike gear so that when the person went to use the bike after like 2 minutes the string tensed up and stabbed the person in the back. Now, you obviously don't copy the exact idea, but my version of that plot device was a hidden knife "gun"... it was just inspired by an episode of a TV show.
while reading/viewing tv and movies can provide ideas, i don't see how it can possibly improve one's imagination... one either has an active/good one, or does not... i don't know that any scientific studies have shown a person can go from having a poor ability to imagine to having a better one through any kind of exposure to stories, or even 'lessons'... does anyone know of such a scientific study/conclusion?...
To grow your imagination, start by spending some time with kids. Young kids. Start to tell them a story, with only the hero and a mission - and then ask them what happens next - and next - and next. Everyone has that kind of imagination - we only hide it away as we 'mature'. Look at anything in the world - a man walking by, a leaf on a tree - and ask yourself "And then what happened?".
Reading helps me better translate, but I am not sure if it improves my imagination. Yes, I am sometimes awestruck thinking how a writer have imagined a story and makes me want to be able to imagine like him/her, but then I have always been a loner who can play alone with imagined friends and anything can inspire me to think. So, maia may be right, nobody can teach you how to improve your imagination or how to imagine, but I think, like everything else, it can be improved. I think it has to come from within, though. How willing r u to think a little deeper about a travial thing like a plant dying somewhere in the park? or, how willing r u to think that the vast universe as we know it may be a small body part of a GIANT being and we are just microbes living in his body? I think the growth of your imaginative power depends on how much you allow it to grow.
I'm thinking that perhaps the habit of writing a lot (even if it is less-than-imaginative) may help, as you are spending more and more time poking around in your imagination. At leasst this is what I am hoping. I've been struggling a little lately when it comes to writing the "meat" of a horror/fantasy story -- I set things up very well, but tend to get stuck when it comes time for the story to kick into gear.