You need:
1. Follow the plot of the game.
2. Prepare potions and buy artifacts in stores, learn spells.
3. Hold joint events with friends.
4. Trust Nel.
5. Actively use clothes and artifacts that are in your inventory.
Celica must actively study, otherwise it will be difficult for her.
In any unclear situation, communicate with the bartender and the fortuneteller. And you don't need to look at these numbers.