Do quests. And use the LFG tool to do instances. You also could do some PvP for xp now too.
The first two are pretty good xp to time rewards.
I think that the PvP xp rates are lower than before, and it fluctuates how effective you are at it.
That or grind on killing mobs. But honestly, chain questing is pretty quick and powerful. The hit or miss nature of the LFG tool I find a little unsatisfying at times. Yet I have heard very good success stories around it.