Check out the search feature of these forums. There are many threads where people have shared there methods. Nothing is foolproof. Remember if you get caught you loose the booze. If that is the worst thing that happens in your life you are doing pretty good.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016
Star Clippers: Royal Clipper 2015