The scoreboard also vastly advantages classes that heal and damage or damage and tank.
The bonus extra-medals for healing 3k & healing done are easy to grab as conceal operative, i.e. - unless you just tunnel. Or if you're a heal - don't forget to throw your grenade for medals & keeping the enemy from tapping and such.
Or if you play something that can taunt... that is supposed to be on cooldown. Doesn't cost a thing and really helps the team...
Lots of small things you don't have to worry too much about and just progressively learn.
One hint: If you keep doing something and it does not work. The solution is probably NOT that it's broken and supposed to work. PvP is a lot about just adapting and trying other things. Sometimes the unexpected 'not best move' throws the enemy off the track and gets you a win.