Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, focus on unlocking key abilities and stat boosts for each character first before branching out. Don’t be afraid to backtrack to grab important nodes. For side quests, be sure to complete the Monster Arena challenges for great rewards and tough battles. Also, don’t miss out on the Celestial Weapons quests for ultimate gear. As for character builds, tailor each one to a specific role like tank, healer, or damage dealer to maximize their potential in battle. Happy exploring!