>>2927683As a new player you'll want to be doing the weekly event matches until you can't progress any further due to stat difference.
Then you find the event match that you autoplay/mindlessly grind without any input from you and run that for event currency.
All the while you'll be leveling girls and hopefully getting useful items from pool hopping events or melon smashing events.
I suggest just taking it easy however. It's a slow grind regardless of how hard you grind. No need to burn yourself out.