In Rift, simply following the Quest Chain is not the fastest method of leveling. There are times where you can gain practically an entire level in under 30 minutes through Rift Events. Also, PvP is a viable method of leveling.
We strongly encourage you to take part in the zone-wide Rift Events. From time to time (about every hour or two), there will be a zone-wide invasion. Meaning, the entire zone is automatically given a quest and everyone's efforts go towards the completion of the quest. For example, one of the zone-wide invasions is called "The Hand of Death". For this quest, the zone must work together to defeat 20 Jakub's Invasions and close 10 Death Rifts. Once the objectives are completed, a raid boss will spawn and must be killed to complete the quest. You must actively take part to receive rewards.
During the event, dozens of Rifts will spawn hundreds of invasions. An invasion is usually a group of 5-10 mobs with one of them being a powerful elite. When the boss of the invasion dies, everyone who contributed to defeating that invasion is rewarded with XP and item rewards. When defeating dozens of invasions and the final raid boss, the amount of XP and item rewards becomes a very high amount. Even at Level 20, I was getting 20-40% of my level per Level 15 zone-wide invasion.
If you are going to take part in the Rift Events, here are a few basic tips:
1. Find out where the central attack point is. This is usually announced before and during the event. "Kelari Refuge is under attack" for example.
2. Stay near central attack points. That is where the invaders are coming. Use your map to find invaders and hover over their icon to see where their destination is.
3. The goal is to take part in as many invasions as possible. The more you're a part of, the more XP and item rewards you will receive.
4. Once the main objectives are completed, some sort of raid boss spawns. Use your map and hover over each invasion until you find the one that's the raid boss. Then travel as fast as you can to that raid boss to get as much credit as possible. Remember, for invasions, the more you contribute the better your rewards are.
Not only is it fun to take part in the invasions, but it's also a great source of XP if done correctly. In the near future, we'll add specifics for each zone-wide invasion.
As for Warfronts, you should complete Koke Tegus' daily everyday, and any other PvP quests once you get them. Not only do you earn lots of Favor (which is used later to buy powerful items), but you'll also earn a decent amount of XP and some item rewards along the way.