"How do I SEO my Shopify store?" For Dummies

Yesterday I spent the whole day at the Shopify Retail tour. They'd invited me, along with a few other folks, to answer questions about Shopify and Ecommerce from existing and potential Shopify customers. From 10am until 4:30pm, I talked to a diverse and interesting lot of folks. But every single person asked me some variation of one universal question: "how do I SEO?"