Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, my top tip is to focus on unlocking key abilities for each character first before branching out. This will make your party more versatile in battles. Don’t be afraid to use key spheres to unlock important nodes early on!

For side quests, be sure to complete the Monster Arena challenges for valuable rewards and tough battles. Also, don’t forget to participate in the Blitzball tournaments for unique items and powerful players for your team.

In terms of character builds, consider specializing each character in a specific role to maximize their potential. For example, Tidus can excel as a fast physical attacker, Yuna as a powerful mage, and Auron as a tanky warrior. Experiment with different paths on the sphere grid to find the best fit for your playstyle. Happy exploring!