Character Motivation
As I mentioned earlier, I prefer to begin my stories with the character and let the story unfold from there. The first step is centred on creating the main characters. The number of characters depends on what kind of story you plan to write. Short stories and novellas generally focus on a protagonist and an antagonist. Novels and series will obviously require more characters.
I begin with the main protagonist because the entire story will centre on this character. I have created character sheets to fill out to develop each of the characters. As I go through the sheets, other characters will sometimes come to mind, but if they don't, I continue on through the steps and come back when other characters jump out at me. I don't try to force this process.
The first thing I do is fill in this questionnaire, which is downloadable:
The next thing I do is make a folder for each character in Scrivener (you can adapt this for whatever writing program you use), and I use the corkboard feature to make index cards for each event I create. The events are taken from the questionnaire. I write one or two sentences describing how I will show that character's development within the story. This includes creating one event for each of the actions the character will need to take in the story.