I just picked this up today at the insistence of my friends. I spent the first few hours dying a lot while figuring out what to do. Wasn't particularly fun at that point.
I saw someone driving some kind of grenade-launching tank around and being crazy and I thought. "I wanna drive a grenade-launching tank!" So I figure out how to get the tank, drive it out. Consulted the map. Drove towards the purply bits. Then when I got there I saw what seemed to be the entire server engaging around a gigantic purple fortress. If it isn't obvious I still have not much clue about the game.
So I drive around being silly, watching as big blue balls fly past my armour in what I think was attempts to either kill me or heal me. Not sure. I happened upon a few dozen of my allies entrenched behind a few buildings trying to push forward into another purply part. So I drive in the direction they're shooting at, turn a sharp corner, barrel past a horde of purple, and smack into the giant purple fortress wall. Apparently I also smashed straight through a few purple dudes as well. I turn around, and see everyone turning to face me.
So I let loose with the grenade launcher. I went from level 2 straight to level 4 in 2 seconds. It was hilarious. I actually somehow managed to even up my kill/death ratio in 2 seconds. It also apparently gave my team a huge morale boost as I saw the few dozen guys hiding behind the walls charge out of the smoke and debris and mop up all the guys left standing. We then took the fortress and I'm still not too sure what exactly I did hahaha.
Then I checked if I could unlock anything and all I earned was a measly 21 certs. Derp.