http://www.cellular-news.com/story/28121.php
A couple of small Faradays for stopping cell phone transmission. Wrapping in foil works too.
The main thing for nuclear EMP is not to have connections to any power lines or antenna lines- any copper connections at all.
A microwave oven is a super good shield, at about 2 gig or so. You’d want to test it by putting a radio inside and see if it can pick up AM, or FM. Try calling your cell phone.
Would you then suggest unplugging the microwave, thereby making sure you aren’t connected to the house’s ground circuit? Serious question.