Assuming you're in a party, from levels 1-12/13ish, just mass murder yellow mobs in Darklight Woods or Frostfang Sea. At 12/13, take your group into Firemyst Gulley, or into Antonica/Commonlands and do any heroic groups you find there. There's an overwhelming amount of them in both Ant and CLs, but FMG is just easier than hunting down and finding the good spots in Ant/CL. At around 18 or 19, leave FMG and go into Thundering Steppes. Mass murder the gnolls around the lakes and then continue down the trench towards RoV. By the time you get to the area around RoV, you should be in the low 20s. Mass murder the skeletons outside of RoV until 28/29. From there, go into EL. Hunt the grinnins along the western shore until you're 32/33, then kill all the grouped goblins that are around the RE entrance/lake. Try to avoid the warmongers, but if you pull them with blues, it's fine. They just take longer to kill. Around 36/37, go into Rivervale and hunt either the Nightbloods in the north/northwest, or if they're contested, go to the faeries/trees in the east of the zone. If all of RV is contested, go into the Feerrott and kill the groups of Lizardmen north/northeast of the Druid port in (there are several places with fast repops here, either around the lake or south of the lake in the ruins). You can do the above two zones into the low 40s, at which point you'll either move into CT or Lavastorm. You can stay in either zone until 50. If you do Lavastorm, just mass murder the grouped heroic goblins at the start of the zone (this has the benefit of dropping goblin language markers so you can then move onto GEBS if you didn't get enough of them from the grinnins/goblins in EL), then move to the area where the Big Squiggly is spawned and kill up that path to the north. Around 47, if your group has significantly better single target DPS than aoe, kill the flare reapers and encountered rumblers around the Fiery Apparition until 50. If your group has significant blue AoE dps, then move into the Temple of Sol Ro until 50. This route is purely about exp and you're going to have to go back and do the other things you're going to need to do your HQs and Speak like a Dragon (no giant language, etc.). The reasoning for this route is a few things: 1) mobs in the open world have, on average, about 35% less hp than similar leveled mobs in dungeons, so they die significantly more quickly, and 2) grouped encounters of single up or no-up mobs that are heroic are both faster to kill than ^^^s and give more exp (exp from each individual mob and the bonus exp for defeating a heroic encounter). Most dungeons do not have a lot of #2 (RoV has a small amount, RE has a lot but is usually heavily contested, and CT).