3. Once you have your computer configured, never directly connect it to the internet again. Consider physically disabling the wireless capability, so it doesn’t get turned on by accident.
Want to Evade NSA Spying? Don’t Connect to the Internet!
And the "no duh" advice of the day comes to you from the fine folks at Wired. Kinda hard to electronically eavesdrop on someone that doesn't use the internet.