Come up with essentials for a story entitled "A Witch Without a Broom."
Begin anywhere but work towards a Lead character. Keep it sketchy at first. Don't burden the story or characters down too much. You want them to be flexible to change as the other elements change.
Once you have a character come up with (or add)
several possible goals. What does this character have a burning need for? What will drive her or him through any and all obstacles thrown their way? The obvious choice is a broom. Why does she want one? Is there a looming event that he will need one for? Why doesn't she have one? He's broke? Her witch family is anti-broom? Why? He's been banned from riding? Why?
The less obvious choice is determination to get by without a broom in a world dependent on the broom? Why? What would drive him against the norm?
As you're filling in essentials, you'll probably find yourself tweaking other aspects. This is good :-) Everything should fit together. A change in goal will affect character, will affect who will oppose him, will affect her character flaws.
Once you've filled in everything ... change the Lead! Change the sex. Do the goals, flaws, opposition, obstacles still fit? How does it change the story? Add more that fit this character better.
Then .. change the Lead again :-) Make him or her 7. Then make her or him 83. Add new goals, opposition. Play around. Have fun with it. :-)
Once you have a good collection, you can cut them up, and draw randomly until you find a combination that feels fresh.
The Lead . . .
Keep it basic and let the goal, the flaws, the antagonist and everything else contribute to the shaping.
The Goal and why the Lead really really must have it . . .
What will happen if she doesn't get it?
What will his life be like if he gives up?
Character flaws that will get in her or his way . . .
Think in terms of character traits that have
helped her up until now. Perhaps begin with strengths. But his circumstances have change and what once worked isn't working so well. (But it's part of his identity so he won't give it up easily!) Or she's carried the strength too far and pushed out traits that could have balanced it.
Examples of Traits and traits gone too far:
Confidence/Pride
Frugal/Cheapskate
Self-sufficiency/Not a team player
Spontaneous/Not a planner
How has this trait been valuable up to this point?
The Antagonist who will throw some of the obstacles between the Lead and the goal . . .
Not necessarily the villain! It could be the Lead's best friend. It's anyone who doesn't want the Lead to reach the goal. If a villain, they want the goal themselves so must prevent the Lead from getting it. If a loved one, perhaps they want to save the Lead from the consequences of these obvious bad choices. (Maybe the Antagonist is right! Maybe the Lead can figure out a way to make it all work.)
Obstacles between the Lead and what he or she wants. . .
Especially ones designed to challenge his or her character flaw.