Don’t worry; it took me a while to grasp the quartz system fully, but then it finally clicked for me. The best part about it is that you can effectively re-spec your slate of spells and boosts any time by swapping your quartzes around the entire party, so you don’t have to worry much about making a mistake in your loadout.
I would strongly recommend prioritizing your sepith budget by opening slots on your two main characters first. Side characters will mostly have their slots open up naturally as the game progresses, but if you have the extra sepith you can open up a key slot or two for them if you need the space to qualify for a specific spell (art). You can find those arts requirements in the in-game manual. If you want to farm sepith to open up slots or buy a specific quartz at a shop, notice what monsters drop the type of sepith you need (your in-game bestiary can help here) and you can target those as you wander about the roads.
I would also advise against selling sepith for money, as there are other ways to make money easily but you cannot gain sepith any way other than combat.
It also took me a while to fully understand the dynamics of the combat system and how powerful the timing of S-Breaks can be since they allow you to jump turns and act immediately, especially when paired with a damage bonus or similar that is earmarked for that turn you hijacked. That realization was a gamechanger.
Thank you both. This is helpful.
My next question is EP. At first, it seemed to recharge pretty reliably. If it was too low to use any art, I would use regular attacks for a couple rounds, and then I’d be able to cast again. Now I’ve hit zero and it has stayed there across multiple battles. I’m not sure what changed. But all my concern over quartz won’t come to much if it turns out that usually you can’t use arts anyway.
My other question is crafts. Do you have any control over which ones you get? Or is this just a basic to each character?
EP is your longer term resource, recharges when you level up or rest. There are special quartz that that can recharge it too, but you get those later. There are consumables too. If I recall correctly, there are some Crafts that some characters get that can recharge EP too. You can prioritize the EP Cut and EP quartz on characters that are more Arts focused. You end up using Arts all the time.
No control over which Crafts you get, they’re pre-defined for each character
I think EP also increases as you open more quartz slots on your orbment. In the beginning you will mainly be resting or leveling up to replenish EP, with maybe a few consumables. Later it will be easier as you have more access to recipes that can recharge EP and money to buy more potions/balms. As you wander, it’s a good idea to buy one of each food item in stores/pubs and eat it to learn the recipe so you can consult your recipe book later and make multiples of the more useful foods and drinks.
Here is a link to the PDF manual, which helped me a lot (it’s for the console version but the game system is the same). The in-game manual is very good as a quick reference, but I always like browsing over an offline manual with this kind of game.