Don't put any charms you find in the game. Charms are very different in their affections. Charms come in 3 different colors: Red, Blue & Yellow. You just need to keep Yellow Charms & put them into your equipments. But if you think you need all of them it's your choise. Try to not sell Yellow Charms & If you see Charm's price is too high it shows that the desired charm is very valuable & better don't sell it.