I recently got the book 'The Cold Counsel: Women in Norse Literature and Myth' which was very interesting! I'd recommend that to anyone, I'm a complete lay person but it was readable and really interesting, it gives a whole new perspective on Norse myths. I also am part way through reading Freyja: The Great Goddess of the North, which I'd also recommend!

The Prose Edda and the Poetic Edda are excellent reads too, but seeing as my copies are old, there are probably even better modern translations out there which I don't know about.

Myth and Religion of the North: the Religion Ancient Scandinavia, by Gabriel Turville-Petre and also The Norse Myths by K Crossley-Holland are highly recommended, as is Norse Mythology: An Encyclopaedia by John Lindow. I'd also recommend reading Mythology, by Edith Hamilton, although only about a quarter of the book is to do with Norse myths, everything in it is interesting, fascinating and readable too.