Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, my advice is to focus on each character’s strengths. For example, Tidus excels in agility and speed, so prioritize nodes that boost those stats. Don’t be afraid to backtrack on the grid to pick up important abilities or stat boosts.

As for side quests, be sure to unlock all the legendary weapons by completing the celestial weapon quest for each character. These weapons are super powerful and definitely worth the effort. Also, don’t forget to tackle the monster arena challenges for great rewards and tough battles.

When it comes to character builds, experiment with different paths on the sphere grid to create unique setups. Mix and match abilities to suit your playstyle, whether you prefer heavy hitters like Auron or magic users like Lulu. And don’t forget to customize your gear for added bonuses!

Happy exploring in Spira! Let me know if you have any other questions or need more tips.