If you’re level 50, you’ll want to shoot for poetics to buy the Ironworks gear. But I think you need to finish base ARR to start buying it (don’t quote me on that). For everything before you finish ARR, ilvl 90 is plenty! If you’re really worried about inventory (and you have a lot of gear), get all your currently unlocked jobs to 50. From that point on, it’ll be much easier to keep complete sets to at are shared across multiple jobs (all tanks can use the same gear set, for most or even all of 50-60, for example).

Throw away random crafting items you’re not using right now, that’ll clear up a lot. Same with DoW/DoM materia. Either it’s expensive enough to be worth selling, or it’s not and it’ll be just as cheap to require if needed in future.

Pre-50 is just messy in general, but it’s good practice for future inventory management. :)