For every subject I took notes. Since your biggest concern seems to be memorization, my strategy is forced recall. After taking my notes for a section (which were really compressed so the minimal information needed was being memorized), I would read them over once, making sure I understood everything. Then I would put the notes away and force myself to recite back what was on them. At first this is going to be pretty slow - line by line and you won't be able to recall all or even most of it. Little by little your retention starts to improve, and you're able to recite bigger and bigger chunks of information without looking at the notes. I would do this for each page of my notes at a time, and once I committed one page fully to memory I moved on to the next. Equally important is that you continue to re-review what you've already memorized to keep it in your head long term. Each day I would try to go back and quickly recite what I had gone through in previous days to make sure I could still recall all of it (again, without looking at my notes but keeping them on hand to glance at and make sure I had actually memorized everything that was on the page) before moving on to memorizing new material that day.
Memorization is really only a big task for the biology section. The amount you need to memorize for QR, OC, and GC is comparatively small (mostly just formulas/equations/reactions).
If you want more detail on how to prepare for the DAT in general, I'd encourage you to read people's breakdowns in this subforum - there are a lot of different resource and strategies you can use. You can read mine
here.
