Inventory/Vault: What should I keep/sell?

[DabMarley]

Hey guys, been playing since Head Start and I'm enjoying the game immensely. The only problem I constantly run into is the laughable amount of inventory and vault space. But I digress...

Something that would help me a lot would be having a better understanding of what I can get rid of and what I should hold onto. I'm constantly hoarding things because I don't know if i'll need them for upgrades/etc later. Can someone please give me the run down of what to keep, and what to ditch? I can't imagine i'm the only one with this problem. 

[Teiji]

Keep weapons are accessories that are required for Hongmoon breakthrough, bopaes that you will use (usually from roulette or heroic dungeons), keys, unsealing talismans, crafting materials, etc.