The game will generally inform you of any secondary mission objectives.
Each mission has from a few to more than a dozen main objectives. Some of them must be completed in a strict sequence, but there are others that provide more freedom (for example, three enemy artillery settlements distributed around the map). In such situations, it is highly recommended to handle them according to the manual – this way you can choose the best route to your destination and you do not have to run back to the places you have already been, saving you a lot of time.
In addition to the main objectives of the mission, a number of optional tasks must be completed, such as sabotaging enemy installations or destroying enemy “elite” troops. It’s a good idea to watch the mission introduction before each mission playthrough – this way you’ll know about any optional objectives before you even start the mission, so you don’t miss out on any of the extra stuff.
Trading cards are one of the secrets of the game.
As with previous installments in the series, you can collect secrets and complete small tasks as you progress through the game. These include:
Diaries – there are 60 of them in the game. After collecting each of them, you can read its contents.
Collectible cards – 20 in total.
Sniper nests – 22 in total. You must reach and unlock each of them.
Longs Shots – There are 8 in total. Each mission gives you the opportunity to get to the Sniper Nest, which allows you to take a long shot and eliminate a specific enemy from a very long distance.
Source: https://guides.gamepressure.com
