* Use a Linux live CD on the "burner laptop" -- don't trust the preinstalled OS
* Change the MAC address of the Wifi used to connect at the internet cafe
* Use Tor, most easily via the Vidalia browser bundle
The author also does not mention that leaking documents can expose the whistleblower via watermarking and user information embedded in the file (most infamously in MS Word documents with versioning).
Edit: update formatting