How to complete a mission without being seen in Sniper Elite 3 [PS4-Xbox One-360-PS3-PC]
Sniper Elite 3 is a game that focuses all on the stealth approach, but completing an entire mission while remaining completely invisible is another story.
Guide Trophy / "Hidden and Brave" Objective
First of all you need to know that you have ONLY been seen by the enemy when he starts shooting at you. This means that if an enemy senses something and starts looking for you, for the purpose of the result you can continue playing because in fact he has not yet discovered you.
Of course I recommend playing a mission (excluding Tobruk, which is not valid for the trophy) on the lowest difficulty. Always use binoculars to tag all enemies, this way you won't have any surprises and you will always know their location.
Use the Welrod (silenced pistol) to take out enemies from close range and use ambient noises to cover up your shots.
The easiest mission to try is the second one, here is a video showing how to complete it from start to finish without ever getting caught. However, remember that if someone sees you, you can always reload the checkpoint and repeat the last piece played.
Important: the guide is ready to unlock all the trophies and objectives of Sniper Elite 3, you can find it together with the others in the Sniper Elite 3 tricks tab.