If you want to earn skill points to unlock class skills in Phantasy Star Online 2: New Genesis you will need to seek out and complete challenges inside both cacoons and towers.
Cacoons and towers are basically dungeon-like areas where you will need to complete tasks that vary from obstacle courses to beating challenging bosses.
Upon completing these cacoons and towers, you will earn a few skill points - cacoons reward one point while towers reward two points at a time or even four. However, this is provided you complete all of the side objectives and meet the time limit goal.
Because of this, you will want to seek these locations out, so you level your classes with new class skills. But where can you find these locations? Well, you can find them all over the world map. You can also find these locations while out exploring the world and during quests.
These dungeon-like locations are also not the only way you can earn skill points for your class skills. Oh no in fact, you can also earn skill points in Phantasy Star Online 2: New Genesis by completing various quests or missions from certain NPCs in the game.
So we recommend checking the rewards on every mission available just in the off chance skill points might be under the list of rewards.
For more on New Genesis, check out Phantasy Star Online 2 Comi Codes (June 2021) and How to play with friends in Phantasy Star Online 2 New Genesis