1. 1. Add your first client (e.g., 'Acme Corp' with email '[email protected]')
2. 2. Create a project (e.g., 'Website Audit' with 10 hours at €50/hour)
3. 3. Generate an invoice linked to the client (e.g., 'Invoice #101' for €500)
4. 4. Mark the invoice as paid when received
5. 5. Check the client's 'Total Invoiced' automatically updated