Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, I always focus on unlocking key abilities first, like Quick Hit for Tidus or Flare for Lulu. Prioritize leveling up your main party members while also branching out to unlock useful skills from adjacent nodes.

For side quests, don’t miss out on the Celestial Weapons and Aeons. They’re powerful additions to your arsenal. Also, be sure to complete the Monster Arena challenges for great rewards and tough battles. And don’t forget about the Al Bhed Primers – collecting them all unlocks a secret scene!

As for character builds, tailor each character to their strengths. For example, focus on magic for Lulu, strength for Auron, and agility for Tidus. Experiment with different paths on the sphere grid to create unique and powerful combinations for your party members. Happy exploring!