I've used aluminum foil with pretty good success. but I fold the edges over and really put pressure on the folds. I do 3 folds per seam. For real protection, I wrap that package in heavy (4 mil plastic) and then do another layer of foil, the same way. Then I do another layer of plastic and another layer of foil.
As far as the micro wave, My BSE brother, told me to tune a standard AM/FM radio to a good station and put in the oven. The radio had no problems receiving the station.
If you've watch any of Dr A Bradley's videos, he demonstrated that using a ham handie-talkie inside a wrapped radio so see if it would receive an RF signal from another radio on the same frequency implied it would show if the shielding was capable of protecting electonics.
Here is a screen shot from onw of his books, showing the shielding effectiveness (dB) of various methods of shileding electronics.
As you can see, the metal tape sealed metal garbage can had the highest shileding if all across all the electromagnetic spectrum. As I mentioned before, I use the triple aluminum foil/plastic insulting barrier wrap. Then it goes into my tape sealed garbage can. What is note worthy is that the good doctor's anti-static bag had a lower value that the aluminum foil.