1. Improve Memory
   1. Spaced Repetition
   2. Interleaving
   3. Longhand Note-taking
   4. Mind Map
   5. Teaching
   6. Improvement on Reasoning
2. For Maturely Developed Domains
   1. Deliberate Practices
3. Short-term Cognition Boost
   1. Caffeine
   2. Nicotine
4. Weak Connection with Cognition Enhancement
   1. Game
   2. Meditation
   3. Brain-boosted Diets
   4. Music
5. Best Hacks
   1. Good sleep
   2. Proper exercise
   3. Testing
   4. Well-rounded Mental Enhancers
6. How to Select the Hacks
   1. Search "Learning Hacks" on Google
   2. Summarize all the hacks and # of mentions
   3. Exclude hard-to-execute ones
   4. Search in Google Scholar
   5. Exclude methods without clinical testings