To increase the succses rate when enchanting you need powerstones, there are diffrent lvl power stones with lower or higher increase. You can buy powerstones from the Item mall when it opens up (no date for thet jet though) or rarly by salvaging equipment rarity grade "uncommon" (green) or abouve, the better the armor part the better the poverstone you may get. Or of course you can buy them from other players.
But since you cant see the succses rate for the anchant anywhere, its hard to tell if the increase from the stones is really worth the high prize they have atm.