A useful first release starts with a clear problem. Describe who faces it, what they do today, and what should be easier.
Separate essential features from ideas that can wait. A short list of important tasks is easier to evaluate than a long wish list.
Think about the systems you already use. Integrations, data migration and access permissions can affect the scope as much as the visible screens.
Finally, define how you will judge the result. Bring those goals to discovery and use them to guide design, testing and release decisions.