I have a preference for graph paper because I can place any idea anywhere on the page exactly where I want it to go. I only use one side of the paper so I don't have to flip back and forth between pages to remember what I wrote.
Using looseleaf paper and a central folder might be more viable for some people vs. a notebook. A nice, new, specially ordered blank notebook can be intimidating to write in. You also have to keep track of a journal to use it. Looseleaf paper is a much smaller mental investment to get the habit started - you can just throw it away if you mess up.
I love definitive reviews like this.
YMMV.
https://www.sacrideo.us/a-quick-review-of-the-diplomat-nexus...
The way this reads is pretty hysterical. I believe he's on here as user "arcfide".
Fully agree with the parent comment about it being like clearing out RAM!
I have also ordered an A6 "pocket" notebook where I want to write one or two sentences or just key words per entry as condensed conclusions to my thoughts or sayings or quotes i heard or read. It should be this condensed book of knowledge and philosophy where long form is not exactly suitable for it.
PS: in my first month, i wrote a lot because there was a lot on my mind. But after a while your brains gets a bit quieter because you are doing this "exercise" and you will go through a short phase where you will be looking for something to write about. That might last a week or two until you settle into the habit and write only when you feel like it. I kinda miss writing when I have nothing to write about so sometimes i just write meaningless thoughts just for the sake of writing. Not all the time, just sometimes.
Journaling off and on since 1987, I have a few rules for myself when journaling:
1. Write the time, day of week, date, month, and year for every entry.
2. Don't worry about lapses in writing. Just write a new entry when I can.
3. Allow my topics to be spontaneous. I sometimes have a structure I'd like to use, but allow freedom in any moment.
4. Relish mistakes, smears, stains on the paper by labeling them, e.g. "tea stain while studying with Akane" (real example!)
5. Just enjoy the process of writing.
As to what you ought to write, maybe start by transcribing some of your favourite poems, song lyrics, quotations, etc. Don't wait until you have some "big thoughts" that are "worthy" of a fancy notebook. Your first step is to see if it feels lie fun to you.
I also keep a journal, but I do that on computer because I value being able to electronically search it.
Shopping lists, random thoughts, UML-like diagrams of code, sketches of possible art pieces, knots, etc. Just anything.
When it comes to practicality... Let's say one does not buy a fountain pen to be practical ;-) These things are fairly maintenance heavy and prone to accidents. There's a reason they have been superseded by several other pen types these days.
Fountain pen is a tool from a different era. One that excels at putting ink on paper in a very comfortable / stylish / craftsman manner...