Along with knowing requirements of major, know what school and professors expect. Read the student manual. You may want to know that professors can’t give tests the last week of school and aren’t allowed to switch your exam time (at D2 school). Professors have leeway in how to grade and what they expect - read the syllabus, find out if they follow the attendance policy, find out if it’s ok to do homework in group or get help on paper (and if you have to disclose - honor code at D1 school). Some of this will vary from teacher to teacher so be sure you know what to expect from each one.
Practical hint from teacher friend - if in large class and you email teacher, attach photo to help teacher place you. Introduce yourself to teachers.