Well I tried to search for this, but I couldn't find a search option (maybe I'm noob I just joined today and posted in the Introduction area)

Is there anything I can do to increase chance of successful enchantment of a weapon or armor?

I tried to enchant a piece of armor and it failed and now I have these crystals in inventory, what do I do with them?

Thanks!

Well i haven't ever found a way to safely enchant unless u are willing to break some others or that aint bug abuse/exploit.
But if u wont mind breaking some others for a +6 set, OE until 3 in a row break and then do the 1 with highest enchant. I never had 4 in a row break
Although i advice this way for D and C grade, or when ur on high rate also above.

And about the crystals, well just sell em or use em for summoning/crafting

you can only safe enchant on a lolserver but on normal servers there is no way to increase chance of sucses enchnat