Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, I recommend focusing on developing each character in their designated roles first before branching out. Use key spheres to unlock important abilities early on.

For side quests, don’t miss out on the Celestial Weapons and Aeons. They’re powerful additions to your arsenal. Also, tackle the Monster Arena for some great rewards and tough battles. And don’t forget the Al Bhed Primers for some interesting lore!

In terms of character builds, experiment with mixing and matching different paths on the sphere grid to create unique builds. For example, you can turn Tidus into a powerhouse by venturing into Auron’s section for extra strength nodes. And don’t underestimate the power of customized abilities like Quick Hit and Hastega.

Happy exploring and may Yevon guide your journey!