Posting my general strategy for PvP because I still have a craving for the beta:
On all the maps that aren't the moon, split off into two groups and take B and C as fast as possible. Ignore the shit out of A. Defend B and C, not by sitting on the flags but by patrolling between them and keeping track of your radar. I would generally stick closer to one than the other to get the upper hand to start killing them before they hit the flag zone.
If one of them is being taken and you're not near it, check how fast the bar is filling up to gauge how many enemies are on it. If it's going fast you'll probably want at least one more teammate with you, because they'll have at least two on it. If you're going in lone wolf I would start sprinting over and then crouch sneaking when near with a rocket or super in hand. After you hopefully kill them, go ahead a little bit and make sure no one is coming with radar, and then cap the flag if a teammate isn't on it. If a teammate is on it and capping it, get your ass back to the other point, either B or C, because they will be coming for it. Rinse and repeat.
For the Moon it's a bit different; head straight for the middle structures as fast as you can every time you spawn. Then I basically do the same thing as above, but instead I move underground patrolling between A and C, and ignore B. Let the vehicles and snipers worry about the outside and B. Also, make sure you get heavy weapons on this map especially, they take out vehicles and turrets fast and they are easy kills in the tight corridors and boxed in flag zones. You should always be getting them anyways, even if you don't do much with them it's better in your hands than theirs.
Lastly, the best strategy; if you're playing with randoms (which I was 90% of the time) pray to the Destiny gods you can do well. You probably won't even have to think twice about things when playing in a decent fireteam against randoms.