Mine uses a Warrior to farm Fire Shards in Chapter 1 in order to Unlock the Knight Class early in the game. This is what i came up so far so. There might be better places you might know of so feel free to ignore mine or share some of your ideas.
Okay so here's the spot that i know of its called Drakegrove it takes 5 Stamina per Entry in Hard Mode.
Its where I farmed the Fire Shards to unlock the Knight Class. So what I did is I used 3 Fire Cards with maxed Skill Seeds to be able to farm that Fire Shards a lot faster.
What I used is a 2* Dust Soldier " Augmented it to get a 2* " with max Seeds Unlocked Same with the other two Salamander Card bought it with Max Boost from the Ability Shop and an Ifrit Card also a fire card with Max Seeds " I got it from the tutorial summon stage" and for the 4th slot a Support Card i just used Yuna for the 4th slot I needed it for healing and just Rent an Earth Card like Raiden to get a Cone Earth Attack or any other Earth Card that you can Rent to able to kill the boss at the last stage much faster its a Wind type Monster. So that's it and you're good to go.
Below is my End Result. I get 102 Fire Shards per run which for me I think its really good already to get the Knight Class much early. Others might get better results using different Fire Cards or in different areas. So yeah feel free to share your opinions
This is the best spot I know so far I might find other spots for specific classes. Like Water Shards Farming for the Mage Class or Wind Shards for Hunter Class and so on. Well I know that not all of you are playing the Warrior Class so I'll try my best to look for a different spot for other classes. Anyway this guide just focuses on the First Map " Chapter One " I know there are others out there that wants to just focus on one class and I myself find it kinda hard to advance on the Stages and wasted like a few stamina repeating with just a Warrior Class that's why I decided to Unlock Knight Class as early as possible to get that Wind Element against Earth type mobs/bosses like in Chapter Two.
I forgot to mention that there's no really a need to follow or copy the same Ability Cards that I'm using for that you might think that you might not be able to do what i did just because you're not using or don't have the same Cards as I am. You're pretty much allowed to use different Ability Cards with the same Fire Element
I hope this information was able to help you guys in any way. Good luck