Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, focus on unlocking key abilities for each character first before branching out. Make sure to use level 1 key spheres wisely to access new paths efficiently.

For side quests, don’t miss out on the Celestial Weapons and Aeons quests for powerful gear and allies. Additionally, tackling the Monster Arena challenges can yield great rewards and help with leveling up.

As for character builds, tailor each character to their strengths. Tidus excels in speed and agility, so boost his accuracy and evasion. Auron is a powerhouse, so focus on increasing his strength and HP. Experiment with different paths on the sphere grid to create a well-rounded team. Happy exploring!