Choose one core problem
Write down the user, the task they need to complete and why the current way is frustrating. The first release should make that one journey meaningfully better.
Separate essential from interesting
For every feature, ask whether the main journey still works without it. Keep a later list so good ideas are not forgotten, but do not let that list silently become the launch scope.
Define a reviewable milestone
Describe what someone should be able to do in the first working version. This creates a clearer review than a percentage-complete status update.
Plan how you will learn
Decide who will try the product and which questions you need answered. Feedback about confusing steps and unmet needs is more useful than adding features just because competitors have them.