The key is to learn the habit of getting started on a task early, i.e. the procrastinator needs to learn to initiate well in advance studying and preparing for papers and exams. Practice starting studying several times every day. As with exercising, getting in control of starting and making it a routine are the secrets.

I note that making things like studying and exercising habits is not necessary to get them done regularly. It is possible to get these done by setting reminders for yourself, instead of making them habits. Making them habits may, of course, be a good idea.