Labyrinth of Refrain: Coven of Dusk

Don't bother grinding with the initial party the game gives you, it'll soon be replaced by characters you make.

An early dungeon navigation skill you get is the ability to break down some walls. These are light brown on the minimap while unbreakable walls are yellow. Some lead to mandatory areas as early as the first dungeon, so fill out every map square you can and don't ignore them as optional.

Gray chests usually have equipment, glowing circles in the game world are items or treasures. An early pace-killing quest requires 10 saltpeter, so don't sell any until after and hit the treasure circles early.

Holding down R, A, or B speeds up combat animations. The game's very grindy, so expect to use this a lot.

Most menus, including combat, have multiple displays scrolled through via the right stick.

Troops are organized in covens. The pact used for a coven defines what dronum (magic) is available to them and some spells require specific slots to be filled in order to be usable. Attack spells work off the average dronum power stat of the group's attackers, but support/heal spells don't care. How you fill support slots mostly doesn't matter unless that specific pact gives a boost based on the soldier's stats, though mages have a skill that boosts the coven's dronum power if it's a caster group. XP is shared among a coven, so slots can be left open if you want to focus on specific characters.

Basic damage types are piercing (purple, usually knight, archer), blunt (yellow, usually mage, dancer, gothic once unlocked) or slash (blue, usually tank, rogue (depending on weapon)) and some weapons have secondary spell element effects. The type of damage is designated by a colored square above the unit's portrait. Piercing is generic, though it seems to especially work on armored characters with visible fleshy bits. Slash is good for enemies with unarmored skin and bugs/plants. Blunt is good for stony/rocky enemies and is particularly good in the first few dungeons. The game says Effective if the enemy is vulnerable to that damage type, Mismatch means the character is in the wrong vanguard/rearguard row for their weapon type.

Battle items are only usable with individual commands (Y button, costs 1 reinforcement). It also allows you to swap characters mid-fight or change to off-hand weapons. Dual-wielding is mostly pointless unless it's either a shobishi with their S+ weapon or you want to use this to swap weapon types mid-fight.

Facet-specific

Astral knight (knight): jack of all trades, can fight front or back row. There's a super powerful spear in the first dungeon if you follow the events, so try to have at least 1.

Peer fortress (tank): Has a chance of taking hits in place of another character that's higher if they're using two katars. A little pointless early, but near mandatory starting around the end of the second world. One early pact requires them to be male, while another just requires them to be created with sun stance which is good for them anyway.

Shinobishi (rogue): They're meant to be dual-wield, but their passive is only for S+ class weapons which means they took moon stance (not recommended since it makes them squishier) or they have sword specialization. Barring those two, just ignore the dual wield and use them as front-line attackers that can handle most weapons. An early attacker oriented pact favors making them women.

Marginal Maze (mage): One of the better support slot fillers since they have a skill that boosts dronum power. A strong early optional pact requires a woman for the attack slot.

Mad raptor (archer): Backline attackers, decent dronum power. Not much to say except they're fast if you have healing/support spells you want to trigger early in a turn.

Theatrical Star (dancer): Backline blunt damage that targets a full group, which is really useful in the early dungeons. They're ok and inflict debuffs mid game.