how to study for dAT

Depends on you. Everyone will give you their own preference. I would probably study them together rather than 3 separate parts. Also, focus on what you are weak in.

 

^^ this sounds like the most obvious advice, but it's really important. when people are studying alone, they often tend to "test" themselves more on things they know, just out of instinct or subconscious or whatever you want to call it. you obviously can't know EVERYTHING, so focus on what you have trouble with.

I would recommend doing each subject all the way through, but as stated above, that's just me. You have to do what works for you.