Some ideas which might help with learning/studying:
Stacks:
Hypothetical Brain-Boosting Stack
Hypothetical Imagination Stack
Hypothetical Productivity Stack
Some general ideas for learning/studying:
Superhuman Genius twice per day at most (before learning/studying or doing something new)
Childlike Wonder x3 (before learning/studying or doing something new)
Induce Creativity (useful before learning/studying or doing something new)
Stop Procrastinating
Dopamine Redux (Google Play , Spotify) or Dopamine Neurotransmitter Overload
Acetylcholine Production (Patreon, The Sapien Trust)
The Super Human Mutant (every 12 hours) x2
Brain enhancement ideas for learning/studying:
Permanent Brain Enhancement
Down Syndrome (might improve memory, plasticity, and cognitive functions)
Nerve Growth Factor
TransCranial Direct Stimulation
Brain Regeneration
I think @gpo may have more ideas. His hypothetical stacks are very comprehensive. 