STAY CONCEALED AS LONG AS POSSIBLE
XCOM 2 offers a concealment mechanic to start off missions. You’re able to move around the battlefield prior to being spotted. This allows you to scan for enemy or objective locations and not get lit up. Once your soldier steps into the line of sight of an enemy (portrayed as a red eye square) or shoots at an alien, your entire squad’s concealment is lifted. It’s always smart to move around as much as possible while concealed to get a good feel of where everything is first. Plus, if you instantly alert the aliens, you are definitely going to be shot up and flanked. They quickly move in to preemptively mess you up, so be the first shot always.