Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, focus on unlocking key abilities first before branching out. Prioritize HP and MP nodes, as well as important skills like Quick Hit for Tidus and Holy for Yuna.

For side quests, don’t miss the Monster Arena for great rewards and tough battles. Completing the Celestial Weapons quests is also essential for powering up your characters. And don’t forget to hunt down the Al Bhed Primers for a special surprise!

In terms of character builds, consider customizing each character to their strengths. For example, boost Tidus’s agility and speed for a speedy attacker, while focusing on magic and magic defense for Lulu. Experiment with different strategies to find what works best for your playstyle. Happy exploring!