Keeping this brief since I’m on mobile right now.

For your opener, generally you prep Standard Step before a pull, and hit Standard Finish as the tank pulls. Then, you start Technical Step. After you hit Technical Finish, use Flourish first, Rising Windmill, Devilment > and then follow the priority system with Saber Dance first, then your hardest hitting procs (Bloodshower, Fountainfall), and then Reverse Cascade last. During Tech Finish windows, you can use Saber Dance as early as 50 Esprit.

For Dance Partner, generally the highest DPS is ideal. So SAM would work if they are the highest DPS in your party. You can kind of use the enmity bars on the job icons to judge who to Dance Partner. Just look for whichever DOS is below the tank in enmity. Otherwise, you have to rely on magical crystal balls that absolutely no one has access to or uses in this game.

If you have any more questions, feel free to rely and/or shoot me a message on Discord. My tag is in my signature.