I thought that Cliff's didn't have enough detail honestly. I mean, chances are you aren't going to be battered with taxonomy on the DAT, but I felt like there is plenty related to it that Cliff's didn't cover that would be fair game. I'd definitely recognize what is a deuterostome/protostome, the coelomate stuff, know all major phyla and generally what they are (i.e. Mollusca are clams, snails etc. with an open circulatory system, and have a calcium carbonate exoskeleton). Know the major domains, kingdoms, etc. Know alternation of generations for plants, and how it relates to each phyla (i.e. Bryophyta has a dominate gametophyte). Taxonomy is definitely one of the more boring sections to study for, but I didn't feel like Cliff's did it much justice. I had questions on top score that I felt were extremely specific relating to taxonomy. I luckily didn't have any on the real thing that were as specific, but I see no reason why they couldn't have been.
As far as best way to study it, I don't have a really good suggestion. I had an Organismal biology class that was pretty good, and I retained a good bit, at least enough for a spark to go off when I saw most phylum names written in a question.
