A User Story kickoff is a short meeting where everyone gets together and has the main conversation about what a story will achieve and how.
A story kickoff should be performed at the last responsible moment to avoid waste - do it at the point you want to start working on the story.
This is the why of your story - what happens if you don’t do this at all? By anchoring back to the why you might be able to pivot to a cheaper or better way of achieving the value in the story. If the so that isn’t clear then maybe you shouldn’t be playing the story at all.
Separate sections for In Scope and Out of Scope can be used to list what is covered by this story and what isn’t. Out of Scope is just as important as In Scope for keeping stories small and paring them down to the most valuable parts first.
Anything from Out of Scope is either covered by other stories already or can be fed into triage.
Break down the steps of completing a story into a task list. This will allow you to easily spot whether the story involves a large amount of work and split it early.