@seaotta the best way is to start writing them!
But IMO a big part is normalising the idea that anything which people would currently write as a tweet thread would be better off as a blog post. Normalising the idea the blog posts don’t need to be polished, or to have stock photos, or even a title.
And then build on that: tweet what would have been the first tweet of the thread, with a link to the full post. Use something like brid.gy to gather responses from twitter as a comment thread.
Might be worth replying to threads we enjoy with “hey, I love your writing, do you have a blog?” to remind people that they exist and would be read