Quick Guide on Path of Exile's Equipment Appraisal
Learning how to check the value of your Path of Exile items, equipment and loots takes a serious amount of time and understanding of the game. It's not something that you learn right off the bat and this guide should help you learn the basics to check which stuff are worth vending and throw away.
We would go through the guide via gear type to make things easy to read and understand:
Chest armor - Life, Resistances, Armor, Energy Shield, Evade
Helmet - Minion Gems, Life, Resistances, Armor, Energy Shield, Evade
Gloves - Attack Speed, Elemental Damage, Life, Resistances
Boots - Movement Speed, Life, Resistances, Armor, Energy Shield, Evade
Shield - Life, Resistances, Armor, Energy Shield, Evade
Jewelry - Attack Speed, Elemental Damage, Critical Boosts
Weapons - Physical Damage, Attack Speed, Triple or Double Elemental Boost Damage
Links come in to play as well when determining the value of equipment. A pair of Gloves may have good values for the attributes listed above but may only have 2 links. That won't be of much value compared to a pair of Gloves with comparable values but have 4 Links; the latter would command a more significant value.
Market values may change as well as Patch Updates are applied. Why you may ask? It's because how it affects the skills and overall aspect of the game. A build may be overpowered at one point then nerfed tomorrow. With that being said, all the equipment's value that's desirable for that build would be axed down as well.
Mastering this aspect of the game comes naturally. My last tip would probably be: if you can hold on to something that looks valuable, it would be best to do so, because that equipment's variables and value may sky rocket tomorrow.