I'd say the easiest way to overcome procrastination is to write yourself a checkbox schedule of things to do. Be specific though. Don't say "study biology", but rather "study chapter 8 in the biology textbook". Divide big tasks into chunks that you can do each day.
I agree. I used to procrastinate heaps, trying to get my high school assignments done the week before they were due (yeah, not horrendous procrastination, but it was still a problem), and I found that if I made myself a schedule of work I would do that day, I would end up doing it. It usually looks something like this:
1 hour of maths
2 hours of IT
1 hour of drumming
In fact, that's what I set myself to do today (I don't have any tests today, and I'm in block exams). It's 1pm, and I've done all of it. It really feels great when you know you've done all the work you had to do that day, and you can take the rest of the day off.