The line counting actually did not work for me at all. It is what I used for crack dat pat. BUT, the objects on the actual DAT are much simpler to visualize than the practice tests.
My tip is to look at width, height, any objects that seem to stick out, and matching lines (dotted to dotted, dotted to bold, bold to bold). The dotted lines are VERY helpful when determining between two closely related answers.
If you are making 20-22 on the practices, you will most likely see the same score on the actual test.
Good luck though!