Moving with the group.
Pressing R to target.
Fields of fire, IE, don't step in front of an assault, or any mech, that is shooting.
If someone does step in front of you while you're shooting, pull up.
Don't stand right behind a peekaboo sniper, so he can back up into cover (my biggest pet peeve with new/bad players)
Don't be afraid of damage, especially in a heavy or assault.
Don't block team mates (I'm thinking the pugzapper on Mordor)
Minimap awareness. Avoiding tunnel vision.
Turning zoom off for close combat.
Mouse settings.
That's all just off the top of my head, and is assuming they are very new players.
Edited by Votanin FleshRender, 10 February 2015 - 10:31 AM.