Most of the time you spend leveling will involve questing and slaying monsters, but there’s also a lot of travel. Travel earns you little experience (you do gain a bit for discovering new areas), so it’s wise to keep travel to a minimum. The new level scaling system, which scales zones to your level within a preset range, helps with that. You can choose what zones you want to experience and stick with them until you finish their quests.
We have no idea what implications this might have and whether or not it even indicates anything, since Patch 8.2 is still in testing and a Tuesday launch is more than unlikely due to Essence tuning and Azshara's Eternal Palace, which is supposedly coming shortly after launch. Blizzard said they wouldn't be delaying the new raid like they did with Battle of Dazar'alor.
Our old friend Quest Helper isn’t updated for the client, but there’s !Questie and MonkeyQuest to help you track available quests and their objectives. The biggest challenge to leveling up in the beta is searching for where the quest objectives are, so if you’re looking to hit the level 30 cap fast — or just the level 5 cap in today’s stress test — you’ll need one of these.