Writing is my primary tool. I keep a blog... and journals. I keep a journal for my reading: what I've read, what I thought about it, choice things I'd like to recall. I keep a journal of my mathematical reading, thoughts, and work. Programming too!
Keeping your writing in a blog and sharing it with others puts a bit of pressure on you to keep a public persona but it's worth doing, as the author points out, to keep one honest. It has taken a while for me to learn this as evidenced on my blog but I have taken it more to heart in recent years.
Be careful writing with an authoritative voice if you yourself have not researched the topic deep enough to convincingly defend your findings! It's much easier for your audience to accept your work if they know you're in the process of discovery when they find an error or omission. It makes you more credible as well.
The more you know, the more you realize how little you know.