Best way is to farm the rare scrolls on the server. Typically the most expensive ones are from Green Glades (GoV 3o3, and to a lesser extent, LS 3o3), but check CM prices, since someone might have glutted the market.
Best way to farm them is find red/low purp mobs, and just kill them over and over. Its a real pain, and takes quite a while (you might get one every 4-5 hours), but last I checked, on Merlin, GoV 3o3 sold for like 50p.
You can also farm the Volcanus mobs for SoM 3o3, Tarts 3o3, and misc other ones like Battler and Bruiser. You'll generally get more, and the mobs are easier, but they sell for quite a bit less usually.
Farming artis imo is a waste of time and a big headache, since you have to run all over to find them, you end up in drama with other players getting them, and generally, there are already piles for sale on the CMs.
For pure cash, if you have a salvager, the orc armies is good, can make about 5-6p an hour from mostly salvage, but its not always up, and it only takes one newb/jerk to ruin it.
Finally, you could always save yourself a bunch of time and just check out Ebay. Plat is pretty cheap now
