I'm pleased to say that as EQ is constantly changing, there are no "tried and true" answers here. The movement of high end players to other games has profoundly changed the bazaar scene. Spider silks are at an all time low, and mid level items are not moving as rapidly. At this time, you are most likely best off farming for items for a vendor sale (gems and plat). If you run a trader, you will have to work extra hard to figure out what is "up" and still selling fast and at a good profit: then, of course, how you are going to get whatever it is to sell.
Most people assume farming is about soloing: you may well want to try a small group. Agree on the loot rules up front, of course. Are you after good equipment? Maybe a non plat approach would work... LDoN gear is good at the top end, and you may be just a short time away from reportedly good "DoN vendor" items.
DS in OoW is, or was, an interesting zone as soon as you can manage the less threatening end: occasional gems, a little plat, XP for you and then aug drops which sell fine.
Good old Ice Giants in everfrost still drop the largest amounts of straight plat. At higher levels, hill giants in rathe spawn faster and are better to farm.
You also need to be "smart"... at least research well. I think i know the value and purpose of virtually every drop from Plane of Innovation. As a result I can walk in, loot a trash mob left rotting with an unsaleable gem, and still make money. I know that it is part of a little, safe quest in PoK which results in a spell that sells for 140p to vendors. As a result, as you REALLY get to know zones, you can keep cash flowing in at a steady pace. I'm not suggesting PoI will make you rich overnight, however.