The baseline 50 opener is going to be something along the lines of:
Hakaze->Jinpu->Gekko (Acquire Blue Sen)
->Iaijutsu: Higanbana to apply DoT
->Meikyo Shisui (cooldown)
->Shifu->Kasha (Acquire Red Sen)->Yukikaze (Acquire Green Sen)
->Hakaze->Jinpu->Gekko (Acquire Blue Sen)
->Iaijutsu: Midare Setsugekka
After that you’ll be comboing to maintain the Jinpu+Shifu buffs and building to 1 or 3 Sen to maintain Higanbana and nuke with Midare.
Samurai AoE is getting the Jinpu+Shifu buffs (either by combo or using Meikyo Shisui to get there faster) and then Fuga->Mangetsu (maintains Jinpu) and Fuga->Oka (maintains Shifu) to build to two Sen, and then Iaijutsu cleave to spend the Sen and repeat.
There’s more stuff as you get higher in level but that’s the ‘core’ of Samurai concept. Everything else is built around that for the most part.
Wouldn’t worry about positionals on Sam - all they do is give slightly more Kenki if you do it right, no extra damage or anything. It’s nice, but chances are your kenki management isn’t anywhere close to optimal (mine certainly isn’t) so just ignore it and treat it as a bonus when it goes right instead of something to aim for.
As for Kenki, the primary uses for it is Hissatsu: Kaiten, which you should be trying to use on any Iaijutsu - especially Higanbana, since it buffs the damage of the DoT for the entire duration.
There’s more stuff to it later with some oGCD attacks and cooldowns and stuff but for the most part Kaiten’s going to be your bread and butter Kenki spender.
There’s also a charge that uses Kenki that’s really nice - most Samurai abilities apart from the core ones (the red/green/blue generators and the finisher) are situational so you usually don’t need to fret about them.
The big one I learned about was the buff that lets you use 3 abilities without comboing them up first - the basic move is to red-blue-green-finisher without all the Hakazes in between but the best use is in the opener, where you can go buff-buff-green-bleed to start the fight.
it is very hard to talk about samurai abilities because you’re either like ‘okay so you first use Daganropa into Flowing Steel and finish off with Tokyo Drift’ or you’re like ‘uh the red one’
I personally open by doing the normal 123 combo to get the 13% damage buff. Then use Hissatsu to buff up the following DoT finisher. And after that use the combo ability to get the big hit finisher almost immediately after. That way the DoT and the combo ability both go off cooldown at the same time and you start off the fight with a lot of damage.
I’m doing the same with red mage, tbh. The basics of ‘balance up your mana, get to 80/80, charge in to melee combo and dash back out’ is really straightforward but as soon as I try and check a guide for how I could be improving my ears start bleeding