Weapons..

The path to getting stronger is long and arduous, nya! It's admirable that you're looking for an efficient route. Don't push yourself too hard or you'll get tired, take it easy, nya!

First, a bigger bag is good because you don't have to come back home as often. After that, I focused a lot on speed and attack power. Increasing the bag size and then attack power allows you to keep completing quests. Then, speed. You also need to raise speed moderately so it's cute when it scurries around.