Before you can systemise a service business you have to see it whole. Most owners carry the business as a set of separate concerns: finding work, doing work, chasing invoices. On paper those concerns connect into one flow, and the connections are where delays, rework and dropped balls actually live.
The four linked stages
Nearly every service business runs the same chain: attract, sell, deliver, and manage the account afterwards. Marketing produces inquiries; sales turns some into agreed work; delivery produces the result; account management handles reporting, renewal and referral. Admin functions such as invoicing and scheduling sit across all four rather than belonging to any one of them.
Draw it as a flow, not a list
Write each stage across a page and underneath it the actual steps someone performs, in order, with the person who does them. Mark every handover with an arrow, since handovers are where work waits. Use what really happens, including the informal steps, rather than the tidy version you would describe to a client.
Look at the joins
Once drawn, examine the arrows rather than the boxes. Typical joins that leak are inquiry to first response, proposal accepted to work started, work finished to invoice sent, and project ended to the next conversation. These gaps are usually invisible day to day because everyone assumes someone else is holding them.
Action Step
Draw your business on one page: the four stages, the real steps under each, the named person for every step, and an arrow at every handover. Circle the three handovers where work most often waits.
This lesson is educational and reflects general practice. Results depend on your situation, market and effort; adapt what you learn to your own context.