Read 6 tips for low-cost academic blogging by Matt Might (matt.might.net)

The secret to low-cost academic blogging is to make blogging a natural byproduct of all the things that academics already do.

Doing an interesting lecture? Put your lecture notes in a blog post.

Writing a detailed email reply? "Reply to public" with a blog post.

Answering the same question a second time? Put it in a blog post.

Writing interesting code? Comment a snippet into a post.

Doing something geeky at home? Blog about what you learned.