On this page of the guide to Aliens: Fireteam Elite you'll learn about further character upgrades, namely perks. You'll also find out how to obtain them and how to equip them in order to maximize the profits they give.
The perks' function
Perks are unique skills that upgrade your character in various ways. It's important to spend some time upgrading the character, as otherwise you might get stuck later on one of the campiagns.
You need to know that the perks are divided into class perks, which are assigned to a specific class, and unique perks which work with all classes. Make sure you're buying a perk your favorite class can use before you make a purchase.
Obtaining perks itself is very simple. As your character levels up, you'll unlock some perks along the way.
Other perks need to be bought with in-game currency from the trader, between missions. Keep in mind that some perks are dedicated to a specific character class.
Equipping the perks is simple, but you need to know that their arrangement matters. The perk equipping screen takes the form of a grid. Bright squares are available, while dark squares are blocked off. They're unlocked only once you reach a specific level.
Each perk takes up some space in the perk grid. It's important to place them correctly, as it'll allow more perks to fit on the grid. Additionally, some perks upgrade a specific skill, as the green squares represent equipped class skills.
Moreover, some perks can be connected with each other, adding an additional effect to the perk.