One of my personal interests is applying the idea of the Long Now. What and how do you write a personal site with the long-term in mind?

If you store your writing on a third party site like Medium or in the complex format used by Evernote or software du jour in time, you will lose the content forever. If it's worth writing, it's worth keeping. The only safe bet at this stage is markdown and git.

There are many benefits to keeping notes as they allow one to accumulate confirming and especially contradictory evidence, and even drafts can be useful so you Don't Repeat Yourself. It also helps fight the fact that the Internet is self destructing paper. A place where anything written is soon destroyed by rapacious competition at pace faster than the internet archivists can keep up with.

"What has been done, thought, written, or spoken is not culture; culture is only that fraction which is remembered."