Well this is obvious...
First I get a small white goat, no older than 4 weeks, and bathe it in a rosemary and hemlock based tincture. Next I extract the blood of the goat using an obsidian dagger, and collect the blood in a tarnished silver bowl. After that I let the blood sit and coagulate for a day, while reciting prayers for good marks on the exam in reverse. It is important that you do not eat sleep or drink during this time.
Next I add water that has never been touched by sunlight into the silver bowl, then a powdered mixture of mandrake root and the finger nail clippings of an orphan who lost his parents at sea (this is really important, if the parents perished in any other way, it won't work.)
Toss that in a Kitchen-aid mixer (one that costs more than $200 but no more than $400, that would just be a total rip off) then apply liberally to the scalp, and boom you're set for your exams.
Otherwise I typically just study.