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 utilize the Expert Sphere Grid for more flexibility in customizing your character builds. For side quests, don’t miss out on the Celestial Weapons and their respective side quests for each character – they are super powerful! And don’t forget to complete the Monster Arena challenges for great rewards. Experiment with different character builds to suit your playstyle – mixing magic and physical abilities can be very effective. Happy exploring!