Many people write journals, but then they also have other things they want to write down, maybe a poem or things that don‘t really fit into a strict diary. May I present to you: the ever trustworthy everything-book!
I personally had one ever since I wanted a place to store my poems in. Then I started to add things I wanted to write down that where important (wisdom). Then I added some recipes, then finally a diary and lastly (for now at least) I added a dream section.
I find it important to still keep order in the book though or it will be of no use. I recommend a DIN-A4 piece of paper, though I do not know if this is a commonly used term in other languages besides German. If not, then I mean: Use a big notebook, about the size of a normal sheet of paper.
This will be useful as you will have way more space.
You want to try to somehow have different sections even though you probably don‘t know how many pages each one requires, as it is work in progress for you. But I think you could guess that journaling requires lots of space. You should probably also try to write the more important things in there, maybe not some random thing like a quick note that you‘ll only need for a few minutes.
Imagine how useful an everything-book will be! Want to look something up? Grab the ever trustworthy book.
When you die, people will have much information about you and it will be very interesting for them. Why would you care? You‘re not in your body anymore.