I have seen many ways of making money...however you will find this guide is much more detailed.

1) Looting

Difficulty: 1/5

Go To Bird Island And Just Pick Up Stuff. Easy Way of Making Money, You Could Make Around 100k Every Now And Then. High levels can loot at Dis city.

2) Buying DB

Difficulty: 1/5

This is the easy way out of making money. I don't do this but if you feel like it, then do it.

3) Lottery

Difficulty: ??

This depends totally on luck. If you are lucky you might make more then you had. If not, then you will lose much more.

4) Composing Gem

Difficulty: 3/5

Getting hold of the gem is a bit difficult. Also do the math and be careful of how much you're going to sell.

5) Blue mouse Quest

Difficulty: 5/5

Need A lot of gems. You want to do this with Divine Hare. Its quite time consuming if you don't find the mouse,. Also you got to do the math, and calculate profit.

6) Buy Low Sell High

Difficulty: ??

You've got to Analyze and Observe . Find out what the price is and you need to take the risk - are you going to sell what you buy? Bit of a risk and you need starting money.

7) Moon Gem Quest

Difficulty: 5/5

It takes forever...but rewards are high. Do the quest 15 times and compose 15 refined gem into Super Moon Gem and sell it high.

8) Mining House

Difficulty: 5/5

Time consuming and you face Pkers and it takes forever!!! Sell the house.

9) Mining In Dc

Difficulty: 2/5

Just mine. you want to have  a decent Pickaxe level and just mine for a few hours....Can make a million or two every few hour from gold ores.

10)  Hunting

Difficulty: 3/5

I hate hunting myself, but people tend to find good stuff...

11) Met Zone Hunting

Difficulty: 3/5

Just hunt all day trying to find the real met dove for 5mets or possible 1db? I hunt at Snakes and stuff...they only drop refined-supers, +1s, etc No Money btw

12)  Moon Box

Difficulty: 4/5

There are pkers here and it is advised to be a lvl 110+ war or tro to do this. It's easier if you have night devil.

13) PKING

Difficulty: 1/5

Well this gets you pk points and everything. It can depend because sometime they drop nothing good!

14) Sky pass

Difficulty:  3/5

Never done this, apparently you can get good reward...if you do do this quest, just choose Box 1 which is recommended. Apparently its a pretty hard quest.

15) Snake Island

Difficulty: 3/5

Recommend archers or high level. I Recommended you have a reborn guard. You get some ok rewards....just need high magic defense....
 
16) Water Farming

Difficulty: Depends

It depends how long you take. If you are an obsessive CO player, then farming doesn't take longer then 24 hours.

17) Gendarme/Titan hunting

Difficulty: 2/5

Well...you don't get much of a reward but they sometime drop exp pots...

18)  Met Spamming

Difficulty: 5/5

Hardly works now, but if you get a socket, money will be everywhere.

19) Squamas

Difficulty: 1/5

Go around looking for squama, hope you get a dragon ball, someone always get one everyday or two.

20) Supering/Upgrading Items Qualities

Difficulty: 5/5

Gotta get lucky on this, and profit and do the math or you'll lose money more then you make

22) Warrior Farming

Difficulty: 4/5

Since they level fast, you could try this...I havent tried this before but its still a way of money making.

Hope it helps...