First, I think the correct forum for this is the Player Questions forum, as this is a location for player-created guides.
You also didn't mention whether this was for heroes or villains or both. That bit of information is critical in answering your question.
Now, being the kind soul that I am 
I'll give you the information you seek (as long as its for heroes. No, I'm not morally opposed to villains, I just don't know the location of that information for villains.)
Clicky
Enjoy
Here is my guide to leveling.
Play the game.
End of guide.
Does anyone know of a good leveling guide anywhere? Like where to hunt between level 10-15, 36-42, etc. and what mobs to hunt.