The difficulty is how many clerics to get gold. Considering that clergy have a limitation as to do dgs on low lvl and really is a class that spends more gold in the game.
I know that in low lvls do not need a lot of gold, but will post tips for various lvls in order to help everyone.
Level 40-50
Recommend doing Evigenia Elite (or difficult case is still low lvl or not having good equipment). You can go running straight and just kill the boss, then repair the dropped items and sells them on the NPC. If it is your choice, it is also good to go killing the mobs along the way in order to obtain more items. Another tip is to go easy on mine Lenfer, normal or hard difficulty. The mobs drop alot of lvl 40-48 and then do the same thing so ... NPC repairs them and Sell them her own.
Level 51-60
Mina elite is the best option. You can go running and killing only the boss (Steuer, Macanga and Malik) or go slowly and killing mobs. A good tip is to actually kill all the mobs dg, on any difficulty, falls and difficulty many items beyond the elite parts set and weapons, also falls Amber and gold materials that can be used to craft some sets.
Level 61-70
Mirza's Air Garden. Ahhhh garden ... a great option for making gold even at high lvl. Maybe you have a hard time doing it even get to lvl 69 or 70. Go easy on every difficulty, and see what your limit. Soon I'll post tips to make garden in every difficulty.
Level 71-80
We have two good options. Cave Lycans or Ariela. Recommend going Lycans. Start by normal and according to your lvl increases, gradually increase the difficulty. There's a good drop. Since diamonds and Kaizes Hiras B and even recipes and rare fragments Jerennis. Not counting the dropped materials that give much gold is sold in NPC. With time and practice you will find the best way to do and the best way. If you choose by Ariela (recommend lvl 74 +), together you can Sources Thunder who drop from mobs with yellow crown. Join 10 thunder, 1 egg and make a brilliant incubator. Open the egg Five Colours obtained and good luck to get a good crystal. The criatais of Ariela Perfect crystals are considered so worth a bit more than those obtained in the Garden.