Don't be afraid to backtrack when you learn new abilities, there's a ton of stuff hidden everywhere, including things you can't even see. Sometimes random NPC give you valuable information on how to progress or find a treasure.

If you get stuck, try to use your parties outside battle abilities, there certainly is a spot you missed.

Don't mute the audio, the soundtrack is fantastic and addicting. Put it on loud.

The original games had a world map included each, I found it quite helpful to not get lost in the world map travel. You might want to find them online, best the original, even if it's just a photo, as to not spoiler more than the original game did with it's paper map. It just had you displayed the cities and geography but not more.

Sometimes backtracking can suck, especially if you walk all the way back from x to y through z, but don't let it get you frustrated, it shouldn't happen too often for the main story. Look at it as training, money farming and invitation to test for hidden paths you might have missed the first time. It's always worth it.

Don't expect to 100% the first time, stuff is really hidden well, but in a fair way. The game rewards experimenting by a good bit.

Enjoy and take your time. It's my most favorite game ever.

Don't be afraid to mess around with the class system and try out things beyond the default mono-elemental classes. There's no penalty for changing your class setup every so often, or even after every fight

The second game has a secret dungeon that is unlocked by collecting all Djinns in both games. No Djinn is missable within their own game, but this obviously doesn't apply across games. You can miss 1 Djinn of each element in the first game and the second one will give you an opportunity to encounter them there to help you out, but that's the end of the leeway.

Nah, just go in blind and enjoy the ride :)