hmph. well, only 29 here, still haven't got demo round, but I can try a few tips.
as the others have said, don't rambo, keep to the back and apply pressure.
In this game, whoever is in the health deficit is almost guaranteed to lose. Since as gunnery you get grav round cheap and as AS you get demo round dot, tab targeting and using these abilities will help the front lines tremendously, as two full health players can kill 4 lower-health ones with correct use of abilities.
A player with 1% health can still do as much DPS/healing/CC as a player at 100% hp, don't go chasing a sorc with bubble on when there's a sniper who can do significant damage to your team right in front of you.
please, spec into the concussive charge/stockstrike knock-backs. In hutball, a cammando using these actually can be a good ball carrier via knocking people off the catwalks, in voidstar you can knock people off the bridges, and in alderaan the opposing team takes longer to capture a base. If there's one situation to rambo, it's when five people are capturing an objective/planting a bomb and that one concussive charge will stop all of them.