Follow one record through the business
Begin with a real workflow rather than a list of software names. A lead might become a customer, then a quotation, an order, an inventory reservation and an invoice. Draw the handoffs and note where someone copies information manually. Those handoffs are useful places to investigate an integration.
Give each record a source
A connected system needs a clear answer to where a record is maintained. The CRM may own customer contact details, inventory may own stock quantities, and finance may own invoice status. These are project decisions rather than universal rules. Decide which module can create or change each record and what the others can read.
Define what crosses the connection
For a CRM-to-sales connection, specify the customer identifier, approved contact fields and deal information that becomes an order. For sales-to-inventory, decide when stock is reserved and released. Include failed updates, duplicate records and cancellations in the discussion; the happy path is only part of the workflow.
Plan access by responsibility
A sales representative may need to see order progress without accessing payroll. A warehouse team may need delivery details without seeing every customer note. Define access for each role and review the sensitive fields that should stay within a module. Use anonymized records when reviewing prototype screens.
Check existing tools before promising a connection
List the software, vendors and data formats you already use. Available APIs, export options, account permissions and vendor limits affect the implementation. Document any manual steps that remain and decide who is responsible when an external service changes.
Release one useful connection first
Choose a workflow that removes a clear source of duplicate work. Test with representative records, confirm the reports and let the team review the result. Keep a rollback or recovery approach appropriate to the scope. Expand to more modules when the first connection is understood and reliable. The goal is a coherent operation, not the largest possible feature list.