Welcome, Commander. If you are reading this, you have likely survived the vanilla tutorial, perhaps even conquered Wrath of the Chosen on Legendary. You are feeling confident. The developers at Pavonis Interactive are about to systematically dismantle that confidence.
Mistake #1: "I brought my best squad."
Tip: The first liberation is incredibly hard. You will need a 10-man squad at 100% infiltration on the HQ assault. Bring a Sharpshooter for the massive sightlines. xcom 2 long war guide
In vanilla, inactive pods didn't care. In LW2, if you shoot, all active pods on the map hear it and move toward you at double speed. The Resistance is a Sieve: The Ultimate XCOM