Go passive and stay passive. Upon 'mech or vehicle start up in the hangar anymore, I immediately go passive. I look for weapon discharge in the distance, or where my teammates are congregating as sign posts for possible enemy activity. Hell, pay attention to team chat, coordinates are usually given by teammates. With the advent of the LT, I go passive almost exclusively. I don't missile much, nor LT as I find them just too boring. Sure, passive can be dangerous if you lonewolf it, but not so much if you stick with your team. And no ping, because as others have said, you give your position away.