Shiny side in or out is a matter of taste. Personally I prefer two-tone with the top of the brim shiny side out and the rest shiny side in. As usual it falls to me to explain the most important factor in tinfoil hats, the pre-crinkling. Scientific studies prove pre-crinkling the foil before shaping reduces tearing, improves shaping, and provides increased durability.
Also too many take the simplistic approach with just one layer. The best tinfoil hats are three layer laminate with the middle being a Faraday cage.