Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, be strategic with your nodes – focus on upgrading your character’s strengths first before branching out. Don’t be afraid to backtrack to grab important abilities or stat boosts.

For side quests, make sure to complete the Monster Arena challenges for valuable rewards and the Celestial weapons quests for powerful gear. Also, don’t forget to unlock the optional aeons for added versatility in battles.

In terms of character builds, tailor each character to fulfill specific roles – like Tidus for speed and agility, Auron for raw power, and Yuna for white magic support. Experiment with different abilities and see what works best for your playstyle. Happy exploring!