Total Control
Your guide will grab your passport and store it for "security reasons" when you arrive in North Korea. Make sure your passport is in good shape and matches the most popular passports in your nation.
Additionally, border officials in the Democratic People's Republic of Korea often take tourists' cell phones upon arrival, returning them only when they depart.
You won't be able to interact with anyone or see anything that isn't part of your pre-arranged tour. You will not gain any insight into the lives of local North Koreans. Your tour will be meticulously planned so that you only visit authorized sights, shop in authorized businesses, and converse with official guides.
Do not breach any of the tour's restrictions; doing so puts your guide in danger. For supporting your "espionage," he or she will be imprisoned and possibly tortured. Follow the guides' lead and compliment each location on your tour, remembering the guideline, "If you have nothing nice to say, don't say anything at all."