Story Mapping
I've used the technique of Story Mapping countless times at project inception to assist in understanding the problem domain area, ensuing a shared understanding of the problem and a collaborative approach to building a product backlog. Unfortunately I can't really claim any credit for this methodology!!
Story mapping starts with an overarching vision of what's required... And is then broken down to a more granular level.
I did this exercise with a large well known e-commerce brand...... Working on high level user journeys within the system- Done with blue index cards - The colour isn't important.. But it's nice to visually see the different types of stories/epics or NFR's (Non functional requirements)
- Browse the catalogue
- Search
- Add to basket
- Payment
Each section was then broken down into smaller stories.... So Payment was broken into different ways of paying
- Card
- PayPal
- Yandex
- Gift Cards
- Account customers
We then tried to find the simplest user journey which took us through the entire system.... drew a line and move everything story which wasn't part of this journey below...
We then began an exercise of iteration release planning.... The teams would be working in 2 weekly sprints with the view of each programme increment being 5 sprints....
We then began to work out what users stories we'd aim to complete in each PI (Programme Increment)

Conclusion
Story mapping is great for project inception... It's allows a backlog of items to be quickly built in a very visual structured way. It creates a shared understanding of what's required and what we're building.
It's also a brilliant way for slicing work into increments... Which also allows us to monitor progress and adjust our release planning!!!

