Here is a basic pre-launch checklist I use when working on a Shopify Project. Of course this checklist can be used on any type of eCommerce project:
Setup the following:
- Email Notifications
- Shipping Handling
- Taxes
- Payment Gateway
- Google Analytics
- Redirect domain name
And don't forget training the client in using the administration backend. Shopify has a great set of resources for support and training:
The first thing you will probably want to do is help your client understand how to organize their products.