Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, I recommend focusing on unlocking key abilities for each character first before branching out to other sections. For side quests, don’t miss out on the Celestial Weapons and monster capturing in the Calm Lands. They provide great rewards and a challenge. As for character builds, consider customizing each character’s path based on their strengths. For example, Tidus can excel in agility and speed, while Lulu can focus on magic. Experiment with different paths to find what works best for your playstyle! Good luck on your journey!