These are my methods of earning easy money in RO..there are 2 ways. But first, you gotta have these
1. A lv 99 whitesmith
2. Have a fire element weapon ( an axe or mace will do )
3. Have max agi and str, rest to dex.
4. Must have the skill greed ( dont have to learn it if your server has autoloot )
5. Max weight on your cart, or nearly max.

Now your ready lets start


Method 1

First get to Geffen dungeon level 3, where the nightmares spawn. Buff up all your skills, equip your fire elemental weapon and start to cart termination those nightmares, after killing one, use greed ( dont hv to if you hv autoloot ). Nightmares drop Old Blue Box and Blue Potions, and also Infiltrator. You can keep the Old Blue Boxes in your storage, so as the Blue Potions or Infils ( if you wanted to get a slotted infil just keep it ). So in quite some time, sell all the stacks of the Blue Potions which sells for 2500 zeny, an increased price for whitesmith of course. And in the mean time, you get old blue boxes, which you can keep using it for some random items ( who knows you might get some good ones.)
Well that ends the method 1.


Method 2
Do you guys know where the Flying Petite is? If not, they're at mjolnir_03, which spawns the most at 70 of them on the map. Well buff up and keep killing these mobs as they drop Gokurin. You might wonder why do you need those. Well guess what? They are sold for 120k zeny each, and a extra price for overcharged. Keep looting these and you will earn your moneyyyy in no time!

Thats it guys, I hope I helped. Isnt it simple and easy? And you dont have to worry bout your hp of your whitesmith cuz u have a max agi which hardly lets the mobs to hit you. Cya next time!! Lol hope I get the elite membership :P