On this page of the guide to Aliens: Fireteam Elite you'll learn about mission preparations. You'll see the possible options and additional functions which make the game more difficult or easier.
Mission selection menu
At first you'll need to choose a specific mission from four different campaigns. After choosing the mission, you can also set its difficulty level. If you're playing with bots (synthetics) we recommend the standard difficulty or lower.
Then you can choose to enable or disable the option allowing you to use Challenge Cards. In the multiplayer mode, please note that if other players also choose a challenge card, the game will select one of the cards at random.
The last option is choosing whether your mission should be public and visible to anyone, private, so that only people you invite can join, or with bots.
Additionally, on the right side of the screen you can see the strength of your team (Combat Rating). It's recommended to always meet the recommended level of the mission.
Starting a mission
Once you've selected all the settings, you'll start mission preparation. Here you can decide, if you didn't do it yet, on your class. After you can choose two consumable items for the selected class, such as incendiary ammo or a stationary turret.
At the very end, each player can choose their own challenge card. If everyone uses this feature, the card will be selected randomly. Please note that after using the card you'll lose one copy of it, and if it was the last card of this type you had, it'll disappear from your inventory.
It is also worth mentioning you have only 60 seconds for all of this, so decide quickly and wisely. If you see that three of your party members have the same class, it's a good idea to pick a different one.