Where is the best place to train in maple story

Levels 1-20 : Go with the flow! Do the beginner quests and beginner job quests.

Levels 21-25 : Kerning City PQ

Levels 25-30 : Subway PQ (Use Dimensional Portal, and go to Construction Site.
(This PQ is like a min Pyramid PQ, only no difficulties, 3 rounds, and there's no huge skill like that big attack that kills everything.)

Levels 31-50 : Monster Carnival doing TW. Or just scam wins :P.

Levels 31-40 (OPTIONAL) : Pyramid Party Quest.

Levels 51-62ish : Mp3 in Singapore. On 2x.

Levels 63- 72ish : Lower Ascent, mob Wind Raiders. (WARNING: VERY HARD TO GET THERE!!)

Levels 73-80 : Twisted Jesters; 4x EXP card.

Levels 81-90 : Fight Balrogs to Witch Bear and you get alot of xp.