After playing Supremacy at the launch of Rise of Iron as well as Iron Banner this week, I thought I'd do a comprehensive strat and tip guide for fellow guardians regarding this new gametype. Hopefully it will help you or any other guardian you think this will benefit.
1) the engram looking items that drop when you get a kill or are killed are not engrams, they are crests. Just in case you're worried about your full inventory, it is safe to pick them up.
2) if there's a blue crest on the floor, pick it up.
3) if there's a red crest on the floor, pick it up.
And there you have it, hope this helps you fellow guardians, as it seems there are a huge number of people not actually picking up the crests which is the only way to score points, you absolute morons..