... could the vets here share some solid squad tactics for OpenXCOM to boost soldier survivability?
Mutual Surprise is very important. Use it to your advantage.
UFOpaedia: "Mutual Surprise" (https://www.ufopaedia.org/index.php/Reaction_fire_triggers):
. If a unit sees an alien at the same instant as it moves into an alien's line of sight, the alien(s) won't reaction fire, even if a unit has no TUs left. The alien spotted doesn't even have to be the alien that spots the unit -- unit can walk through a door and see an alien ahead, which will prevent unseen aliens to the side from attacking.