It's important to spend time reviewing your syllabi each semester. Things to make sure you take note of:
Your instructors contact information and office hours
Exam dates
Big projects
Papers & assignments
Record that information in your planner, Google Calendar, phone-pick a method and use it consistently throughout the semester.
The Center for Academic Success and Transition (CAST) provides a downloadable tool called The Syllabi Matrix that allows you to capture the most important info from your course syllabi. You can get that here: https://success.unl.edu/CAST%20-%20Syllabi%20Matrix.pdf
More details at: https://success.unl.edu/CAST%20-%20Syllabi%20Matrix.pdf