I'm thinking of giving Samurai a try in Stormblood, though only after I've capped and geared my Dragoon.

As for preparations, I wasn't really intending to make any, but just by happenstance I ended up finding a really good Ronin costume on my Paladin. I might look into finding a version of it that non-tanks can equip, so I can save it for a future Samurai.