How do I use Readwise if I don't have that many highlights yet?

While you're building up your own collection of digital highlights, you can "supplement" your Daily Review with popular highlights from books you've read using Supplemental Highlights. (This is also great for integrating audiobooks or physical books into your Daily Review!)

Supplemental highlights are generated automatically from the most popular sections of books in Readwise.

Although these supplemental highlights are obviously not quite the same as your own personal highlights, reviewing them can be surprisingly effective nonetheless!