An e-commerce site on its own is a shop window. When it doesn't talk to the ERP behind it, stock, price and order data get carried by hand and become unsustainable as volume grows.
01. Four Core Flows
Product and price from the ERP to the site, stock from the ERP or WMS to the site, orders from the site to the ERP, and shipment and invoice details from the ERP back to the site. With those four in place most of the operation runs itself.
02. Price Management
Price must have a single owner. Managing campaign prices on the site and list prices in the ERP is a common approach, but the rule for which wins in which case must be written down.
03. Stock Freshness
Real-time synchronisation isn't always necessary; what matters is fast-moving products. Pushing changed products frequently and the full catalogue once a day is the most balanced answer in practice.
04. Order Transfer
Order transfer into the ERP must be repeatable. A unique-key check preventing the same order being transferred twice is the most basic safety net in the integration.
05. The Invoicing Side
The invoice is issued in the ERP and sent as an e-Archive document, with the invoice number written back to the site. Letting customers see their invoice in their account noticeably reduces support load.
06. Monitoring
The integration's last run time, pending record count and error list must be visible. A transfer job that silently stops costs both sales and customer satisfaction until someone notices.