Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, focus on unlocking key abilities first before branching out. Prioritize HP and MP nodes for survivability and magic nodes for spellcasters. Don’t forget to use the teleport spheres to backtrack and access missed nodes.

For side quests, be sure to complete the Monster Arena challenges for valuable rewards and AP. The Celestial Weapons quests can be tough but are worth it for the powerful weapons. And don’t miss out on the Al Bhed Primers and Cactuar Village for fun extras!

As for character builds, consider customizing each character to suit different roles in battle. Tidus and Wakka make great physical attackers, while Lulu and Yuna excel in magic. Experiment with mixing abilities from different paths to create versatile fighters. Have fun exploring Spira!