Gear Up Progression

[Okamimaru]

Centurio seals are obtained from hunts... Tbh the gears from centurio seals are pretty much just for glamour now... tomestones are your best for good gears for now... they are easy to obtain and the shire gears are decent... relying on dungeon drops to gear is also not a good idea because of rng making obtaining them unreliable... again best for glamour... last option is buying gears off the market board... depending on your server it can be expensive or really cheap....

[Vineas]

Hei Crimson, just want to share with you my experience so far.

I stayed with Ironworks set until my char lvl 60, and then I do the Class Quest where it gives Antiquated Armor Coffer (ilvl 200). I used the Antiquated Armor until I reach Idyllshire before changing to Shire Sets (iLvl 220).

Centurio Seals can be obtained once you get to Ishgard. Just need to do the preliminary quest in the Inn near the Forgotten Knight aether point.
In my opinion, just spend your seals on Antiquated Weapon and Accessories, you will be fine wearing the whole Antiquated until you reach Idyllshire.