First understand the current flow of data, then the MVP end-state flow of data, then the complete desired end-state flow of data. Next take the advice posted by

First understand the current flow of data, then the MVP end-state flow of data, then the complete desired end-state flow of data. Next take the advice posted by wjossey and implement the most minimal end-to-end MVP that flows that data. Last, iterate until you get to good enough.