Map

A good stealth mission starts with the players entering from a direction orthogonal to where enemies expect them to come in. Thus the first areas are less well patrolled and the likelyhood of success is high.

Show players the map generously, but use line of sight to determine if players can see enemies. These stealth rules work best when the map has clusters of open-ish areas that are cut off from other areas. This prevents a botched attempt at stealth from spilling over into the rest of the battle map.