Reddit mentions of Witchcraft: Theory and Practice

If you want something a little more poignant and less "fluffy" read anything by Ly de Angeles. She's very thorough and has more of a direct approach than many authors. She avoids the Wicca stuff (which many refer to as "fluffy bunny paganism") and just goes for the guts of it.

There's a very broad base of beliefs under the "pagan" umbrella and Wicca, though very popular these days, is only one facet of such. Try and vary your reading from Cunnigham to de Angeles to Crowley (even if he's not your thing, it adds to a broader perspective/understanding).

I've found that studying any religion or philosophy it's good to read from a broad base of sources. MockingDead also lists several other references for different styles.

I've never really read anything apart from this, and it's probably not what you expected when you wrote this post, but when I was looking into Wicca and Witchcraft, there was a book by Lys De Angeles (this one: looked it up for you just in case) and I'd only gotten through the first few exercises, but I managed to get myself in a trance doing them one night that felt like I kind of lost myself for a while and drifted away someplace. Not sure how long it lasted because I lost track of time, but I ended up unbalancing and falling over, snapping myself out of it (was on my bed, didn't get hurt) It was definitely some intense meditation there, kind of creepy, but VERY effective and I still use some of the techniques for calming my mind down when I get a little anxious in public. You could probably find some pages to download a sample ahem ahem instead of buying the book, because I'm not sure how useful it would be for your purpose past the first couple of chapters that go beyond clearing your mind and being able to visualize things in your head.

EDIT: spelling