If you do Crucible, raise your crucible rank and buy the gear from the outfitter. PvP marks can be used by any of the factions, so while you get the marks you can also be ranking up your faction levels. If you are like me and you do mostly PvE, then just keep plugging away at the strikes and patrol missions until you can get gear from the Vanguard. You might get lucky with engrams, but that's a roll of the dice.