Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, my tip is to focus on each character’s strengths. Make sure to unlock key abilities like Haste and Cure early on to make battles easier. Don’t be afraid to backtrack to previous nodes to get stat boosts either.

For side quests, definitely don’t miss out on the Celestial Weapons. They can be a game-changer in tough battles. Also, make sure to complete the Monster Arena challenges for great rewards and to unlock some of the best abilities on the sphere grid.

As for character builds, I recommend specializing each character to fulfill a specific role in battle. For example, Tidus can be a speedy physical attacker, Yuna can focus on white magic and summoning, and Auron can be a powerhouse with high strength. Experiment with different paths on the sphere grid to find what works best for your playstyle. Happy exploring!