How I take notes:
For professional life: Pen + dot grid notepad - developed independently, but similar to the bullet journal technique. Dot grid plus pens make the whole thing ultra customizable. I can sketch engineering designs, make a calendar, track action items, take detailed notes, all in the same format. The key is to be strict with page numbers, dates, and index as much as possible.

Things I occasionally miss - keyword search (I can still look things up by date or subject in the index), multimedia inserts (think dragging video/photos/sound clips into one note), never ending space (notebooks run out of pages), easy backups (thinking about digitizing with photos or scans), team collaboration (if this is necessary I use Trello).

Things I like - no OS/tech stack compatibility issues, "it just works", lighter then a laptop/tablet, don't need to charge, easy to read, can bring into a secure area (where outside electronics are not permitted), travels well, hard to damage.

http://bulletjournal.com/get-started/

For personal life: add Google keep for simple lists, and then a mix of Trello and dot grid for larger projects (less strict formatting than professional life project management).

How I index using pen/paper:

Every page has a number in the upper outside corner.

Every entry into the note book has a title + subject tag, date, and the initials of a list of people linked to that entry. For easy reading and scanning I put all of this on one line. The title and subject are dark lined (thick), followed by the date MM/DD/YY, and then the initials inside a ( ). Each piece of info is separated by a ";". All of the info listed is underlined.

under the intro line, I also break down actions, notes, calendar adds, etc with 3-4 different symbols. All I all this makes it clear and easy to scan quickly as you are looking for things.

Each month I have 4 or 5 pages devoted to organization.

I have a task list. Two bulleted columns. Old tasked are migrated over from the previous month. New tasks are added as soon as they are generated. Completed tasks get an X through the bullet. Migrated tasks get an >. Tasks that are linked to journal entries get a page number and a tag.

I have a calendar page. 1 column, all dates of the month listed . Meetings, important actions and events are are listed by day, or with arrows over multiple days. Linked by tag/page number if applicable.

I have a subject index. Major tags, reoccurring subjects, get a line or two. Page numbers with those subjects are added to the index.

I realize this sounds complicated, but it's not once you get into a routine. The biggest this is it's okay to make "mistakes", and to get used to not having a delete key. Change is part of the notebook. Think of it like a change log. It's also important to be able to see what you change. Since I work in pen, I just make a single line through things I want to change.

Note: when I finish or complete something on a task list or the calendar, I'll mark or change the symbol, I won't cross something out just because I'm done with it.

Finally, I have a bunch of multi color pens I use. They are all the same brand/model, but I tend to use a different color each day. That makes it obvious as you are scanning that you are on the next day. I don't use specific colors for anything in particular, too hard to keep track of.

Hope this helps.

Reposted from an older thread @
https://news.ycombinator.com/item?id=17799232

edit - notebook choice is important. I use something like this (https://www.amazon.com/Dotted-Bullet-Notebook-Journal-Hardco...)
Not an affiliate link.
Its sturdy, you can't pull out or add pages (which is a feature), bound and stitched, decent quality paper, dot/grid, and normally under $15/book.