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. Don’t be afraid to backtrack to grab important nodes. For side quests, make sure to complete the Monster Arena challenges for great rewards and the Celestial Weapons quest for ultimate weapons. As for character builds, tailor each character to their strengths – for example, magic for Yuna, strength for Tidus, and agility for Wakka. Experiment with different paths on the sphere grid to create unique and powerful builds for your party members. Happy exploring!