The rule that answers most of it
Keep a material if a camp level you intend to buy or a recipe you intend to forge names it. Sell everything else. That sounds obvious until you try it, because the game does not tell you which of the rusty-looking trinkets in your bag is the one blocking Warehouse 7 — it just shows you 503 possible items and a storage bar filling up.
The reason this rule works is that reserving is cheap and hoarding is not. There are only three or four named materials per camp level and three or four per recipe. Everything outside those short lists is sale stock. Once you write your two lists down, the decision at the vendor screen stops being a judgement call and becomes a lookup.
There is one correction worth making before you start, because it changes what "keep" means. Mistfall Hunter has no salvage and no disenchant. You cannot break a piece of gear down into materials, and the developers have said that no such system is planned at this time. Unwanted equipment has exactly two destinations: a vendor or the auction. Holding it "for materials later" is holding it for nothing.
Reserve against your camp first
Every camp upgrade costs Gyldenblod plus three or four specific collectibles, and those collectibles are the single most common thing players sell by accident. Scavenger Squad 1 wants Charcoal ×4, Copper Button ×2 and a Soulcall Flute. Warehouse 2 wants Fishbone, Fine Salt, Copper Button and Pearl Dust. Shop 2 wants Fishbone, Vine Bundle, Slime and a Velgr Feather. None of those names look valuable, and all of them stop a build cold when they are missing.
The practical move is to open the camp screen, look at the next level of the two or three buildings you are actually saving for, and note the twelve or so material names that appear. That is your reserve list for the week. Anything on it goes to the Warehouse; anything not on it is stock. Redo the exercise when a building levels, because the lists change completely as you climb — the late Warehouse and Soulcatch Tree levels want single copies of Gem of the Gods, Vronn's Forging Hammer, Immaculate Egg and Faded Divine Tree Heart, and those are worth real money if you sell one by mistake.
Two shortcuts help. First, the same materials recur across buildings — Pearl Dust, Gem Mirror, Norgard King's Coin, Dragonslayer's Banner and Penitent's Tear each appear in several upgrade lists, so they are almost always worth keeping a spare of. Second, if you are not sure what something is, look it up before selling; the item entry lists what it is used for, where it comes from and whether it can be traded at all.
Then reserve against the forge
Crafting materials are a different category and deserve a different rule. Recipes like Studded Sword and Shield want Meteoric Steel Ingot ×1, Copper Ingot ×1 and Waxwood Branch ×2; Convergence Staff wants Fine Wood, Resin and Crude Runestone ×2; Tier I Agate wants Agate, Resin and Seashell. Those are common inputs, and crucially, many of them are sold for Gyldenblod by the Premium Shop once you have Shop 2 — Meteoric Steel Ingot, Copper Ingot, Fine Wood, Hard Leather, Linen Fabric, Agate and the Crude, Improved and Fine Runestones all appear on its shelves.
That changes the calculation. A material you can buy on demand does not need a shelf in your Warehouse; a material you can only find in a raid does. Keep a small working stock of the purchasable commodities — enough for the next craft or two — and sell the surplus rather than sitting on forty ingots you will never queue. The Flawless Runestone tier and the rarer collector pieces are the ones worth genuinely stockpiling, because they gate the Tier II gem recipes at the top of the forge list.
Tavern materials sit in the same bucket. Hero's Ale takes Malt ×3 and Hops ×1, Warblood takes Hops ×3 and Wild Berries ×1, and Gods' Brew takes Wild Berries ×3 and Crystal Nectar ×2. Malt and Hops are cheap and shop-bought; Wild Berries and Crystal Nectar are worth holding if you actually drink before runs.
The things that are never sale stock
Ciphers are the clearest keep. They are legendary scrolls you extract from a raid and hand to a specific camp NPC, and the flavour text on each one hints at who should receive it — the six that ship are Ancestral, Bloodbound, Shadow, Elder Edict, Echo and Ashen. Handing one to the NPC its text points at adds a chance of a bonus item on top of the base payout, so a cipher in the right hands is worth more than a cipher on the market. This is a completely separate system from unidentified loot, which is ordinary raid gear identified through a timed pickup inside the raid; the two get confused constantly and they share nothing.
Time-limited items are the opposite of a keep — they are a use-now. Repair kit vouchers and Pip's Pouch vouchers ship with durations attached, like a Fine Repair Kit for 7 or 30 days or a Pip's Fine Pouch Voucher for 3 days, and the clock does not care whether you are using them. A Gyldenblod Gel is the same idea in reverse: its own item text says using it yields 400 Gyldenblod plus a chance at an Epic, Legendary or Holy item, so there is no reason for one to sit in storage.
Then there is the category you cannot sell even if you want to. Some items are simply not tradable, including the Soul of Return you need to leave a raid and the Gyldjar that carries Gyldenblod home. Keys are the awkward middle case: there are hundreds of treasure and access keys, named per area, and carrying a Treasure Key - Prison into a run where no prison exists is pure dead weight. Keep the keys for the areas you run and clear the rest.
Gear you did not plan to use
Because there is no salvage, every unwanted piece of equipment is a pricing question rather than a recycling question. Before anything else, pull the gems out. Gems come out at the blacksmith and directly from your inventory or Warehouse, they are listed separately from equipment on the auction, and a socketed gem sold inside a piece of armour is a gem you gave away. The affix and gem lab is the fastest way to check whether the gem you are about to lose was one you actually need.
After that, the choice is vendor value against auction return, and it genuinely depends on the item. Commodity materials in stacks tend to move fast; a niche class-locked Epic may sit on a listing slot for a day and still expire. Experienced players disagree about which is better on average, and the honest answer is that it differs by item class — the comparison itself is covered in auction house and vendor pricing.
One caution about rarity as a keep signal: rarity is a weak predictor of usefulness in this game. A gemmed low-rarity piece routinely outperforms an empty high-rarity one, which means the Epic you cannot socket may be worth less to you than the Rare you can. Judge a piece by whether it fits the loadout you actually run, not by its border colour.
Stop hoarding, structurally
The reason your Warehouse refills after every clear-out is that keeping has no visible cost while selling has a visible one. You feel the Gyldenblod you did not get; you never feel the slot you wasted. Fixing that means putting a cost on keeping — a rule like "one stack of each shop-purchasable material, and nothing else without a named use."
The storage math will not rescue you either. Warehouse levels go from 128 slots up by +448 across thirteen levels, but the late ones cost 10,000 Gyldenblod each, and the developers have said material stack limits will not be raised. A dedicated gem warehouse with its own stacking and filtering has been promised in time for Season 1, and a wider personal warehouse expansion is only under consideration. Plan as though the space you have now is close to the space you will have.
The last piece is discipline about what leaves camp with you. A bag full of speculative pickups is a bag you cannot fill with the thing you actually came for, and everything in it is at risk the moment a fight goes badly. Deciding the value of a run before you enter it is the subject of building a loadout you can lose, and it pairs directly with this: what you refuse to carry is as much of an economy decision as what you refuse to sell.
Where to go next
Start with your own reserve list. Open the next level of each building you are saving for in the camp planner, write down the materials, and treat that list as untouchable for the week — the reasoning behind which buildings deserve that saving is in camp upgrade order that works.
Then run one pass over your Warehouse with the list in hand and price the rest properly rather than dumping it. Checking an item's stated use in the item database takes seconds and it is the single habit that stops the "I sold the thing I needed" post that appears in the community every day.