If you haven't already, work on Rhapsodies progression. The gear sets in the guide are current, but most of the gear past the low tier level is from Escha/Reisenjima, which you'll need gain access to via RoV missions.
Additionally, you get a lot of bonuses from the KIs rewarded as you go. Little of it should prove challenging in what you have (and the upcoming patch is apparently nerfing stuff too).
Once you have access to Escha/etc, ideally, XP/CP there to build Silt (Domain Invasion can be a great way to gain that as well).
I would also put priority on fleshing out your spell list, since the Adoulin nukes, Mighty Guard, etc are pretty key. To add to that, get augmented/reforged Relic feet if you don't have them, and ensure you have full Diffusion merits (to maximize potential time you can have Mighty Guard on).
Gear priority depends a lot on what kind of help you might be able to get, if any. In general, I would definitely plan to build up a nuking set as well, since that tends to be a far faster way to gain Job Points (much less merits for HTBs).
If you're soloing, your target will likely be Alluvion Yorcia Skirmish (also a convenient place to learn a lot of spells). Then building up to Escha Zi'Tah, and so on. Quite a lot can wind up being doable with trusts as you get better geared/JP'ed/etc.
Depending on help (and zone access), you could also just go get Ru'Aun abjurations and Herculean gear and so on handed to you, or something in between. So, it's hard to say for certain what your next logical step is, outside of making sure you've got access to the appropriate zones.