Premium content can mean any type of content you charge for - an ebook, whitepaper, downloadable guide, etc. But what I'm referring to here is pay-gated content. Basically you just put some awesome content up behind a paywall, which means visitors pay to access it. You can get your own paywall set up in 10 minutes or less using a plugin like MemberPress or Paid Memberships Pro.
Quality content is content that people can engage with and find useful. Your content should help readers and bring them value. Your blog needs to have interesting, helpful content that people would be willing to recommend or share with their friends. The format, structure, layout (and, of course, the writing itself) will all determine the quality of your blog.
Make it easy for readers to browse – If you want more pageviews, you should make it as easy as possible for readers to read your other blog posts. You will want to make it easy for readers to find your blog homepage, categories, tags, search bar, and so on. Also, I recommend including links in every single one of your blog posts, so readers can easily find related topics.