Answer by Alex Sumner:
A good all-round introduction to the subject is Enochian Vision Magick by Lon Milo Duquette, which is essentially how one would go from being a complete beginner to a practising magician in all aspects of Dee’s system. Once you have that out of the way, you are ready for Dee’s original materials. I recommend John Dee’s Five Books of Mystery, edited by Joseph H Peterson, and Meric Casaubon’s “A True and Faithful Relation…” now published as Dr. John Dee’s Spiritual Diaries: 1583-1608, edited by Stephen Skinner.
Some years ago themagickalreview.org even had high quality scans of Dee’s diaries online, but unfortunately their site seems to be down.
Sol Ascendans - The Website of Alex Sumner 