I’m not going to recommend a spirit as that’s been addressed in other threads, but to create your own talisman using Mercury’s kamea or planetary square.
Pick a word or two for your intentions such as ‘memory’. Then convert it to numbers using Pythagorean numerology.
Then you’ll chart the numbers in order to create a unique sigil on the kamea. Activate your sigil and then keep is on your person. If you edit it on the computer, you can resize the kamea after adding the sigil to a size small enough to fit inside your shoe.
It also wouldn’t hurt to learn studying tips you can readily find online such as using a mneumonic device. One that helped me was to read the first line of a paragraph and then the last line of the same paragraph. If it made sense, move on. If not, read the whole paragraph. Re-read the whole thing at a later time. That and handwriting notes has better retention than typing them out. Good luck on your exams.