What you will need:
A spring of Mint
A stick of Cinnamon
A cup of water
Small pot or cauldron
Athame or Knife
Wand, or stirring rod
Cup, goblet, chalice... something to drink out of.
This potion can serve any number of purposes related to mental strength. It can be used to increase psychic awareness, strengthen comprehension skills, induce prophetic dream, and has many uses beyond those listed here. It's preparation is simple, and the potion itself also has an enjoyable flavor when finished.
Cinnamon has always traditionally been used to stimulate the mind and increase Spiritual vibrations. Mint is generally associated with healing, however it has also been used to cure headaches. The purpose of it in this particular potion is to reduce the sometimes-painful effects of study or divination.
Enchant the Mint and Cinnamon for the purpose you have in mind. It is important to enchant herbs before using them in any potion, to help attune their natural energy for the purpose you want them to serve. For this particular potion, increasing mental strength and psychic awareness is the general purpose.
Using your Athame (Or a clean knife, if you prefer not to use your Athame, many traditions believe that it should never be used for cutting, I personally use mine as much as possible to attune it's energy), cut all the leaves from the sprig of mint. Slice each leaf in half, and place all pieces into the water. Place the pot/cauldron onto your heat source, and place the Cinnamon Stick into the pot. Repeat the following incantation seven times, stirring the potion with your wand (or stirring rod if you prefer not to use your wand) three times with each recitation:
It is my will that this potion will strengthen my mind.
If you wish, you can write your own incantation to suit your needs for the potion. It does not need to rhyme, just be sure that it's a clear statement of intent, and do not use any words with negative connotation (Can't, Won't, etc). Continue stirring with your wand or stirring rod, and visualize yourself studying, meditating, or dreaming. After an additional twenty-one stirs, let the potion heat. Once it begins to simmer, let it continue for three minutes before removing it from heat.
Be sure that whatever container you plan on pouring the potion into is clean, and fit to drink from, and can safely hold hot liquid. Remove the leaves and Cinnamon Stick from the potion; discard. Pour the potion into your container, and allow it to cool for at least 10 minutes before drinking. When you drink the potion, focus on exactly the purpose you wish the potion to serve.
Clean off your wand, Knife/Athame, and wash out your pot/cauldron and whatever you drank the potion from when complete. It's a good habit to have; you don't want residual energy from previous potions mixing with any potions you wish to make in the future.