@Salutation
I did not take any classes, but I did have a private tutor.
The Science section is kind of like the reading. For the science section, I first looked at the questions before proceeding to the graphs/tables/reading. Do not waste your time reading the tables/graphs/reading before the questions because a lot of the stuff there is not asked in the questions. For the fighting scientists section, lets say that there are two scientists. I first would answer the questions that relate to scientist 1, then answer the questions related to scientist 2, before finishing the questions that combine the viewpoints of all the scientists.
For the reading section, I first would skim through the passage. For the questions without specific line/paragraph citations, I would quickly look through the passage, and if I can’t find the answer, I would just go with my instinct because I found out that I would usually get the questions right. For the questions with line/paragraph references, I would read the entire paragraph the lines are in because there you can understand what the passage is talking about.
The main enemy on the ACT is time, so you have to be very careful with time management.
I took ~8 practice tests in the Math/Science, but ~12 in the English and Reading sections because those are my weaker sections.