Don't know what happens next? Answer these nine questions.
To generate a plot, alternate Scenes of Action (the protagonist actively pursuing a goal) with Scenes of Reaction (the protagonist crafting new plans and goals after the previous goals have failed).
Scenes of Action must have clear and specific answers to the following questions:
1. Who wants what and why?
2. How do they intend to get it?
3. What is stopping them from getting it?
4. What unexpected event finally quashes their plan?
In thesis form: [Character] aims at [goal] because [ultimate ends], and they try using [means] to get it. But [antagonist] blocks them. Then an [unexpected event] renders [goal] a nullity. **
The disaster that ends the Scene of Action causes the protagonist to retrench, leading to a Scene of Reaction.
Scenes of Reaction must have clear and specific answers to the following questions:
1. Who suffers the pain of failure, and what does it feel like?
2. What possible courses of action open up to them?
3. What are their new near- and long-term goals?
4. How are they going to achieve their new goal(s)?
5. What is the first thing they do in trying to achieve their new goal?
In thesis form: [Character] feels [emotion] after failing. [Near- and long-term goals] shift due to the changed circumstances, and [character] contemplates [possible new goals] and [possible new plans] to achieve them. [Character] decides on [new goal and plan] and embarks on [first overt act] of the new plan.
As the character overtly acts toward the new goal, the story enters a new Scene of Action.
* * * * *
In every scene, whether of action or reaction, you are selling emotional involvement to the reader. Glengarry Glen Ross tells you how to make the sale.
Scene of Action: Always Be Closing
1. The characters have a goal. They should always be closing on it.
2. Never let the reader forget the goal, the stakes, and the character(s)' need to reach it. Make them believe it.
Scene of Reaction: AIDA
A. Attention: Get the character/reader's attention with a failure to reach a goal.
I. Interest: Fixate the character/reader onto the changed situation.
D. Decision: Get the character/reader to willingly invest in seeing the goal reached via a new plan.
A. Action: Absorb the reader into the story by making the character actively pursue the goal.
** "Nullity": Either the protagonist is thwarted in achieving their goal; or they achieve it and realize it was the wrong goal; or they achieve it and nevertheless find themselves in a worse spot than if they had not achieved it.
Sources: Dwight V. Swain and David Mamet.
For more: "Storytelling Catechisms"