Shiny side out!
(Jeez, another SF loser!)
It can't be stressed enough how important it is to have the shiny side pointing out. This is needed because the shiny side is most reflective to psychotronic radiation, while the dull side can actually, in certain environmental conditions, absorb it. However, as is illustrated in the instructions above, it is also wise to complement this with a layer of foil pointing shiny side in. This will keep your brain waves, which are also reflected by the shiny side, from being picked up by mind-reading equipment. There is a small number of aluminum foil researchers who believe that this may cause an alpha-wave harmonic to build up in the skull resulting in memory loss or pseudo-religious visions, but their findings have never been replicated by the aluminum foil research community at large. Even if their findings are validated, the risk involved is small compared to the potential of mind-intrusion.