Planning is very important in the early stages of story development.  Thinking and turning it over and writing down notes are very important for not only plot but also characters.  However, in the end, the most important thing is: just writing.  Planning too much for too long can slow you done and easily leads to tangents; you’ll plan way more than you’ll end up using or needing.  The only real way to meet your characters face-to-face is to write.  That’s when they take the reigns and tell you where you’re following them.  There has never been a character I’ve made who hasn’t tweaked their originally planned personality.  Not to mention those wonderful plot breakthroughs that can only be found with writing.

And just to note, many people say to draw out a map to flesh out your world.  Maps are useful but not necessary.  In fact, sometimes they’re positively deadly to natural imagination.  Things you naturally see in your head can be so much harder to put on paper.  You start to try to be so exact and mention everything about that world of yours right off that tangents and time-wasting can run rampage.  And though it’s important to give your reader the sense that you know about the world your writing and a sense of a larger, real world, it’s very necessary to let that world come to you in its own time and grow with the story.  There may come a time, a time I’m experiencing now, when your world has outgrown your head and you simply can’t contain it all.  This is the perfect time to start noting and sketching what you know and imagine down on paper, but again, this may lead you to become, shall we say, disillusioned with your world.  Suddenly, nothing really works!  So keep it simple, don’t get too fancy, and let it sit in your mind for as long as you possibly can.