Regarding about the reinforce

Someone have some tip in reinforcing the equipment to +30 or is just a pure luck :(

From 25 is just pure luck. S rank skin smith is the one that gives the boost on reinforcing tho. With the smith skin, you can achieve +32 fairly often. +35 if you invest a lot (more than 10k reinforce scroll in my case). I saw someone who achieved +38 without using diamond but this doesnt usually happen.