My advice is to not worry about it. If you complete the mainline quests of the world before the one you want to enter, you will be high enough level to enter . Just follow the mainline. If you complete a lot of sidequests or adventure in sideworlds like Wysteria or Grizzleheim before you first enter, you will be higher level, which is fine.
Some people seem to get all worried about being "overlevel" for their world. I don't understand their concern. There is absolutely no downside to being higher level than the minimum necessary to enter a world. It just means you have more health, more mana, more power pips, all of which make things easier. Why does anyone care about being "overlevel"? It's silly to worry about it.
I need to know I been seeing people who are in dragonspyre that are level fourty something.
it all depends on a few factors:
-do you play frequently, or only once in a while? -do you complete all quests (main and side), or follow the storyline only? -do you play alone, or with friends? -in what order do you complete worlds?
for example, my balance wizard completes all quests and left dragonspyre at level 52-53. she finished celestia around level 60 (which was the cap at the time), then went off to wintertusk.
my necromancer, who follows the main arc only, fought malistaire at level 49 and was well into celestia at the same level (52-53); however, i found him underleveled and sent him to wintertusk first before returning to celestia at level 63.
generally speaking, though, here is a pretty good guide:
