well items that are colored red, for starters, dont sell them yet and uae them as mich as possible. crafting in this game is not really the crafting your thinking. its more like socketing crystals to make it another type of powerful equips (called Mythics). Another items not to sell, if you any item with 4 sockets. Gather as much as many gold as you can. you can change your skills later with Amber, a very rare crystals. convertion is a vame mechanic to take an item or 2 to sacrifice to create next powerful item, like on crystal, converting 2 calcite will give you angelite.