Leveling Guide....

[Taluvill]

1-5: Newb zone
5-13 or so: close dungeon or close zone (IE: Crushbone/NRO/Blackburrow, etc)
13-17-18: Oasis. Unrest works well if you can get there untwinked. Can ride Unrest through 24 if you want to.

20+: Sol A. Uguk. MM entrance.
33-34+: Lguk, Possibly Sol B if your lucky. Kedge if your smart, but its very tough.

40+: Sol B all the way to 50. Possibly the lower parts of Lguk.

This is basically a grouping guide. Solo/duo classes have much more freedom.