Hey fellow Final Fantasy X adventurer! When it comes to sphere grid progression, focus on unlocking key nodes like HP, MP, and important abilities first before branching out. Don’t be afraid to backtrack to grab missed nodes! For side quests, definitely tackle the monster arena for great rewards and tough battles. As for character builds, customize each character based on their strengths – Tidus for speed and agility, Auron for power, and Yuna for magic. Experiment with different paths to suit your playstyle! Happy exploring!