In the article where Cory Doctorow describes his writing method, he mentions the original meaning of the word "blog", web log, which was meant to be the logbook of you journey through the web, a kind of annotated browser history.
For every input you find interesting, try to express what it is that you find interesting, why it is significant for you.
Writing about something you've read requires clear thinking, especially when writing for an audience. These post, when properly tagged and searchable, become a personal repository of previous thoughts and sources. This repository, in addtion to the memory formation from thinking deeply about a topic, make it easier to integrate the source/topic into a longer story/article/essay.
I find this idea fascinating, because I have read a lot of things over the years, and I have forgotten most of that. I do keep notes, but I don't think they work as well as what Cory describes. This is probably something that should be explicitly taught in schools or early in university.