I always like to have 2 techniques and test them against each other.
When I "prepped" for PAT, I put my tic-tac-toe grids on the top half of my paper. On the bottom half, I divided it into 6 even boxes. In each of those boxes, I would put a small square in the top-left corner. In that small box, I would first count how many cubes there were in the ENTIRE structure, and write it down. when I finished counting my cubes' faces, I made sure the numbers matched up.
When you're looking for "hidden" cubes, remember this (because I had a lot of grief with these with CDP) you can only have a "hidden" cube if you can clearly see that there is another cube sitting on top of it. I did, in fact, have a hidden cube thrown at me on DAT (but it was pretty clear, though I think it could have thrown me off if I hadn't seen it in practice). When looking at the hidden cube, count them with the x,y,z axis. When all the cubes are the same size/color, they can make your eyes cross. When that happened to me, I would just count the bottom "layer" first and try to "block it out" (what I mean by block it out: sometimes you can quickly count cubes by seeing them as groups--for me, I would frequently get 8-block, 6-block, and 4-block combos). If you can get used to quickly visualizing this, you're half way there.
When you block out your cubes, you can much more easily keep track of your hidden cube.
Potential pitfalls from here:
1.) Always look for what's behind your hidden block. Are there more blocks behind the layer you're looking in? A really common trick I noticed was to put blocks not DIRECTLY behind your hidden cube, but maybe 1 space behind. This will expose the hidden cube's backside.
2.) Again, ONLY count a hidden cube if there's one sitting right on top of him. If you don't see a "floating" cube, never assume one is there.
If this is confusing, let me know. We can do a screenshare or skype or something and I can help you out more!
Also, as I was writing this, I saw your reply to my breakdown. Thank you so much!!! You've got this!
