Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, I recommend focusing on each character’s strengths. Make sure to unlock key abilities like Quick Hit for Tidus, Doublecast for Yuna, and Mug for Rikku.

For side quests, don’t miss out on the Celestial Weapons – they are super powerful when fully upgraded! Also, tackling the monster arena and unlocking all the aeons is a fun challenge. And of course, don’t forget the optional bosses like Penance for the ultimate test of your skills.

As for character builds, experiment with mixing different paths on the sphere grid to create versatile characters. For example, giving Auron some white magic abilities can make him a powerhouse healer in a pinch. And don’t underestimate the power of abilities like Auto-Haste and Auto-Phoenix for survivability in tough battles. Happy exploring!