wendiq, me again.
I actually think the Design Originals books by Suzanne McNeill are great for beginners, because they are very basic and not overwhelming. Her first book (Zentangle Basics) is not a favorite of mine; I found it was not quite explanatory enough, if you know what I mean. I also have her books #2 through #8 and they are very good and contain a lot more explanation about how to do each Tangle. Another Design Originals book is Joy of Zentangle; that's a really great one.
The books by Kass Hall and Sandy Steen Bartholomew are a bit more advanced, in my opinion. And I second someone's recommendation of the tangle patterns website; she really does a good job in putting everything together.
I wish you luck in settling down long enough to enjoy doing some tangles! That's the hardest part, to shut off one's brain and just go with the flow...