Don't worry about stats and substats until you hit endgame. Until then, you'll be swapping out gear so much that it doesn't matter. And at endgame, aside from materia, gear given stats only matter if you are going for Best in Slot, which will require savage raiding to achieve.
Speaking of Materia, you are gonna be getting a bunch of it as you progress, but generally don't worry about it. Materia is strictly only needed at the endgame to tweak your stats so you can kill bosses before enrage (which generally only Extreme and Savage bosses have).

And I would give a different order of stat importance than QooEr said:
Weapon damage >>>> main stat (dexterity) >> skill/spell speed to taste > crit > dh > det

"To taste" meaning however much you need to comfortably complete your rotation. This varies from class to class wildly. Dark Knight will want a certain amount of skill speed so they can use Bloodspiller 5 times during Delirium. Black Mages like having a certain amount of spell speed so they can get off their 3-4 Fire 4s in a row without Enochian running out of time. However, a class like Summoner doesn't need spell speed that much since most of their spells have no cast time. I have no idea whether Bard needs skillspeed, but the balance will tell you.