A great checklist for advanced Shopify SEO.
Quick Tips from other sites, worth keeping for reference.
An excellent case study on migrating from Magento to Shopify, using cart2cart and a shipping estimator.
Change the document root folder using htaccess. Make life easier with your root site in a separate folder.
Official Shopify blog article about how to add liquid code, to facilitate Related/Recommended Products on your Product page