What should I use to enhance rings? Any specific armor level or special ingredients?
Converse with fellow players
Each ring has a set of materials it needs. You can see what that is when you go to enhance the ring. It is a mix of stuff like grinders, rocks and gems from gathering etc. etc.
On top of that, when grinding them you have to select a parameter to upgrade with it. the ones that use attack, choose the type relevant to the ring you're upgrading. Example being if I upgrade a JG Sonic Arrow Ring, I'll be using that on Hunter, so choose Melee obviously. For rings that ask you to choose a defense type to upgrade just choose whatever you think is best, imo I use melee def. Grinding rings is pretty painful. Stock up on materials and wish for the best. Risk reducers can sometimes ease the pain.