One of the interesting debates among writers is the whole outline/plan vs. spitting it out. I've always been more of a "get it out" type of writer, but I also find that sometimes I plan or outline how I think a story's going to go because I don't have time right at the moment to finish, but I can at least write out the basic idea, since I know that once I break the flow of my thoughts, the writing may change directions when I return to work on that piece.
That said, sometimes I think writers forget to address another phenomenon that tends to happen - sometimes the story we think we're writing turns into something else. And what, pray tell, might the catalyst of this metamorphosis be? In fact, many times it is the voices of the characters themselves.
Now, this might seem a little odd - after all, aren't I in control as the writer? But the truth is, stories take on lives of their own, as evidenced by innumerable interpretations of literature and poetry. So, too, does characterization. But I think there's a lot of reasons for this.
When I teach story writing to my students, one of the things I have them start with is the characters. Pick how many characters there will be, and what are their ages, backgrounds, wants, etc. Often times, this tells the novice writer something about their story. For instance, I had a student who wanted to write about four friends getting together at a cabin. One of the characters was very shy, liked to read, and enjoyed knitting. I told my student that tells us, at the plot-creators and audience/reader, that means that this character will probably not be up to date on sports, or maybe the main characters are not meeting to going skiing or hiking. It's a fairly simple way to approach writing, but sometimes it saves me a lot of time. And sometimes, I just get inspired.
Recently, I was writing a short story. It was a bit of an experiment for me - lots of humor and zombies, both of which I have little experience. So I just started jotting down some things. At some point, after wandering around with my prose and trying to figure out where the story was going or how it would end, I finally realized what my character wanted. I wrote the rest of the story that day because I listened to that inner voice that assumed the persona of this character I had brought into being.
Now, I'm also an actress, so in some ways, it's quite a similar insight. I don't have to go steal or knife someone to play a character that does. I simply study the behavior and let it inform my choices when I'm onstage. True, zombies aren't technically real, but the way my character communicates itself is, so I can use that to connect to the audience.
The bottom line is, I start stories all the time. I get story ideas all the time. But a lot of the time I'm not sure what to do with them or where they are going. What do I do? I skip to the parts that I want to write and let the character show me which way the story is going that allows them to get closer to what they want.
So sure, go ahead and plan. But just we sometimes have to throw our plans out of the window due to unforeseen circumstances, we also just need to let the words - and our characters - have their way with us.