How do you guys use your time & agenda efficiently? How do you guys get your studying/homework done?

Hi all!

I'm going to post-secondary as a freshman in Spring 2014 and I'm really nervous. I'm actually most nervous about fact I didn't do so well in high school and because of that, those habits I've developed back then might effect how I well do in post-secondary. I always left studying the night before for a test and sure enough, I always do terrible on tests. I procrastinate a lot back in high school. There was this school project where I had a month to do so and my teacher gave us time in class to do, yet I ended up doing EVERYTHING the night before the due date. However because time was running out, I ended up not even handing in the project.. And gosh, I really don't want to be that kind of student in college. I want to change. 

For starters, I think I need to get my goals straighten out and I also need to use a school agenda to manage my schedule. 

However in high school... in the beginning of the school year, I did use my school agenda yet I just became lazy and ended up not using it at all. So I'm really worried about falling into that habit.

So that being said, how do you guys use your time and school agenda efficiently?