If you want to get more out of it than just pleasure then you need to find apply some manner of critique and analysis so that you learn something from it. It's more involved than just reading a book, you need to understand various schools and forms of criticism, from purely literary to historical and a mash mash in between.

You can either watch some videos that introduce you to literary analysis, you don't need a whole degree in it but some basic understanding to get you started so that you're primed to go through a book with the right tools in mind. Or you can do it backwards, read the book first as normal and then read in depth or academic reviews and see what elements the reviewer is focusing and seeing if that's something you noticed or not so you then build up those same tools but in a different manner with which to go into your next book and repeat.