How to avoid friendly fire:
1. Notice a non-stop strafer in your team.
2. Leave the game immediately.

how to aviod ff,simple stay well back from demos,roll backwards if u have to^^ and dont play with cross platform players eg strafers if u see it happening in game just leave, i do in most occasions on higher diffs,use the screwing around challenge card they soon get the message trying for that awesome kill^^its funny u standing still yet they still try run past you,only to fall on there arse,perfect excample,im a lancer standing still in a hallway there is left and right of me plenty of space basically with a drone incoming -1 dude saw a drone coming and ran on my right side to get to it first,good news i rolled knocking the pro player down:) after he fell down ,the drone grabbed him killed him basically instantly on extreme.we went on to clear the rest of the mission with no ff and no problems,great safety card and is fun to use^^ great way to sus out the strafers.

I have done that ( no frendly fire couple of times in different mission and level) but.. I dont get achivements in steam.. any one knows why? is that becouse not of all team reached? ia all of us 3 need to have no frendly fire?

thanks!

Open your eyes.

How is this hard?
Just don't click your team.

Tip #5; Don't use flame throwers... LOL

@MOK This

Good luck finding players who understand this.

#4 Is the #1 tip

No. Strafing. Ever.