We are surprising to find the fact that most maple story powerleveling players did a lot of works and trying to make their maple story powerleveling up.
Grouping when it is not necessary - When you join a group, you will get less experience points for each kill than if you did the quest yourself. It will take much longer time to level up. Grouping is nice, but not efficient.
What to do instead: Quest alone, and avoid the quests that take two or more players to succeed. You might want to do them later at a higher Maple story powerleveling, or not do them at all. The only time you should group, should be for dungeons, or if you are two or more to arrive on the same spot to get one quest item.