Source: Book: How to take smart notes - Sönke Ahrens
Always keep a slip of paper, or your trusted pocket notebook, and a pen with you whenever you're either
- Reading an article, book etc
- In a meeting
- Working on a project
- Etc And take a note of any worthwhile idea you come across. On the back of that note, write the reference details (for eg, page x in book, or article etc).
Notes should be taken in a handwritten form, in your own words. Target brevity, just jot down few keywords that'll help you reconstruct it later on when you add permanent notes. Hand writing notes help here, since you're limited by the speed. Copying or highlighting text digitally is less effective, since you take the text out of the context, and it might not strengthen your understanding the way handwriting does.
Next go through your handwritten notes, preferably daily, before you start losing context and start forgetting it. And convert them into permanent notes with full details and necessary context, so that when you comeback to it in future ignorant of what it is, you can still understand them. Note that your note is written from your point of view. People with different interest read same text with different views and focus on different things. That's fine and exactly how it should be.
Your note should discuss one idea/thing at a time. Keep the note concise so it ideally fits on a single screen.
Reflect on the note, and try to find connections with your other existing notes in your notebook. Think about questions and problems to which this note contributes. Ask things which are not stated. Try to find contradictions. Your notebook isn't an archival system where you just dump things and forget, instead make it your thinking. Do you really understand the thing at hand? Try to explain it in your own words. Look for things you can't explain. That's your feedback, work on that. Also connect it with your other notes. Have a dialogue with your notebook. Your focus should be on understanding.
For adding keywords/tags, instead of picking it from the text, use a topic your working on or interested in. It should reflect the circumstances will you stumble on this note.
Add links, on the note to other relevant notes, also on other notes linking back to this one. These interlinks is how you should discover information/connections.
Add a index entry if needed, which acts as entrypoint to your notes about a topic. You shouldn't add every note to index, instead just 3-4 notes. And then you discover other information through interlinks.