You've just started a brand new project for building a product. How do you get started?
First you have to understand what this product is supposed to do for it's consumers. What goals they want to achieve with it? What tasks do they carry out to achieve these goals?
That will be the most important part of your story map. That's the scope what your product might support in some way.
Next you'd like to find out variations on how to support your product's users fulfilling their tasks. How can your product help them?
For example: How can the Online shop's customers find the product they need?
What are the most important tasks for your product's audience in order to achieve their goals?
Sign up and Sign in may not be needed at first. Customers could order without signing in to the shop with the
drawback that next time they'd have to type in all their data again.
On the other hand finding the product seems to be a must.
After you know the must have tasks, what are the tasks from these that needs IT support the most?
Maybe ordering could be done on the phone first. Maybe not. It depends on your customer's business.
You'll pick the most important from the proposed solutions with your customer and schedule them into the first release.
Why is it so important? We'll see it in the next step.
While you're elaborating and developing the planned solutions, you might realise that you've missed some necessary tasks
that are being done by your product's audience (How products are added to the shop?). Then you add them to the story map, and find out solutions
on how these can be supported by your product.
You might also realise that some of the solutions need much more effort than you thought. Then you and your customer could say: Ok, in "browsing by categories" we don't really need hierarchical structure at first, we could live with a flat list. The other features are much more important for us. And add the hierarchical categories into unscheduled items, so that it won't be forgotten.
On this journey you'll find out that it's far from a known path. You'll discover the domain,
your customer's needs and her customer's needs. You have to rethink and adapt all the time.
You'll come up with better ideas. You'll want to manage those ideas, those features.
You'll want to manage the scope to come up with a product that supports your customers the most. And you'll want to achieve that on time.
That's where user story mapping and StoriesOnBoard can help you.
For a deeper explanation on user story mapping see Jeff Patton's amazing work.