After you are 52, it's time to equip B Grade Gear. That means another trip to Giran to visit the GM Shop.
At 52, you have a lot of choices for leveling. You can go to Oren and then to Outlaw Forest. You can go to Aden and try out the first floor at the Tower of Insolence. Explore the map between Oren and Aden.
At 61, you can equip A grade gear, so head back to Giran and get ready for the grind to end game.