Before you start studying, make sure you've got everything you need.
On your table should be class notes, the syllabus, required books, teachers slides, the tools you need, and ideally examples of previous exams so you know the structure and how it'll be graded.
In your fridge there should be superfoods: almonds, fruits, veggies and yogurt should do the job.
Even if your brain's weight is only around 2% of your body weight, it uses up around 20% of its energy.
To avoid procrastination, shut down all distractions and tell your friends not to disturb.
Ideally you should start studying weeks before, but let's assume that you have just 7 days and 3 hours a day.
On day 1, your aim is to get context, to see the big picture.
This is important, because context acts like a memory network, to which you can attach all details.
First you make connections and then later remember things easier.
To get there fast, read the class syllabus, skim through text-books and review all the materials without going into details.