You should make a priest and use Magnus Exorcismus In Gefenia dungeon level 2 thru 4, just autoloot everything, when ur inventory is full 100/100, head to go 11 there is NPC right away You can sell those there and warp back to dungeon. This method can make 50-60M in an hour not counting the cards You get. Also I think it's best if You put Stackable items like potions etc into storage and later sell them with Merchant. You can buy blue gemstone at @go 9 Magic Items Seller, or U can buy Mistress card if You decide to dedicate purely to this method.
Requirements for this:
-High Priest (lvl.255 would be ideal)
-Teleport lvl 1
You can aswell try to farm Thanatos tower, @ autoloot everything aswell (stone of sage is main source of income), You can go Thanatos tower levels 7 thru 10.
For this I would use LK, because they walk faster with pecos (since u can not teleport on those maps) and they can hold large amounts of weight.
The another method would be farm "Mavkas" at Moscovia Forest lvl. 3, Autoloot Witherless roses (@alootid +748 and crystal mirror @alootid +747, You can aswell autoloot Blue Herbs, since they are RUSH for alchemists, You can sell them on trade @alootid +510 for that)
Then there is aswell an option to farm Amistr Eyes in Bio Laboratory Underground (lvl4 on warpra). You need basic gears for this thought, since it's a lowrate drop.
Amistr Eyes are really LIT right now u can sell just 2 of those babies for over 1 credit! You get lot of useful stuff aswell like Glistening coats, Acid bottels, OCA's and Clips of Cinciousness, You can always profit selling those aswell.
You will need following:
-Any slotted shoes (Dark Lord card)
-Any slotted armor (Orc Lord card)
-Any slotted shield (Alice card)
-Novice Angra Manyu (until U get premium one) <-This is VERY important, You need the angra to get healed back from reflect.
-Any slotted garment(raydric card/deviling card)
-Slotted headgears (Rata cards)
To get these basic gears U can first grind up any of above methods, since these are pretty easy and do not require any special gears.
Hope this helped a bit ^^
P.S. When U have Your 4 slotted angra, buy 4AK cards and head straight to new MVP rooms! It's worth it!