I'll never forget the day my professor walked into class and told us that our negligence would make it impossible for anyone in the class to receive an A. The only thing that exceeded our surprise was our confusion. Why all of a sudden could none of us get an A?
We hadn't checked our syllabus. The professor explained, quite frankly, that our syllabus required the scheduling of a meeting with him before the sixth week of classes. However, all of us simply did the homework assigned in class and didn't bother to check the syllabus for anything extra. It was a real wake-up call, and to this day I’m wary about checking my syllabus.
My best advice would be to use a planner. Once you have all of your syllabi, writing down important dates can save you in college. Even if you aren't super organized (guilty), throwing reminders on your phone for exam dates, project due dates, and finals schedules is an easy way to keep yourself from missing something important.
Your professors won't make their syllabi for no reason, almost everything they include is important. Your syllabi serve as a reference for your whole semester. You can go back to them to check things from homework to attendance policy -- crucial for 8 a.m.’s. Referring back to your syllabus regularly for each class can't hurt, I'd even recommend taking a quick look over them once every two weeks or so, just to avoid the shock of finding out you have a project due the next week, or an exam the next day. Professors don't always tell you when things are coming up; it's important to be accountable for what they give you.
If you're wondering how my class ended up after our professor told us that we couldn't receive A’s in the course, it ended up being alright. He cut us a deal; if we made the meeting happen within the next week we would be alright, otherwise ten points off the final grade. Most of us met with him the next day, and did not miss our next required meeting.