A new application is rarely the starting point. The starting point is usually a moment when work gets stuck.
Follow one task from beginning to end.
Choose a real request, order or approval. Note where it starts, who touches it, what information moves with it and where someone has to re-enter data. Keep the first version of the map simple enough that the people doing the work can correct it.
Separate the problem from the proposed feature.
“We need a dashboard” is a proposed feature. “We cannot see which orders need action” is a problem. That distinction leaves room for a smaller and more useful solution.
Define the smallest worthwhile change.
A first workstream might connect two systems, remove a duplicate step or make an exception visible. Agree what improvement you want to observe before expanding the scope.