Plat(Platinum) , which caps out at 100plat per trade/inv (or 1000plat for stash) which is still used to trade smaller things such as mini's and for materials
Ecto(Ectoplasm) , are used in place or higher value items (like rarer mini's,collectors items etc...) also used in terms of trades since plat is normally used for scrolls/armor upgrades etc... and harder to get ahold of large amounts
Arm(Armbraces) , these are used for tormented weapons, or get such cases as ultra high end items (Rare collectors items/Ultra Rare minis"Polar bear,Panda, Kanaxai etc..) (Normal trades cap out at 1500 ecto or 6 stacks of 250)
9-13 Ecto = 100k plat (depending on the days ecto value)
1 Arm = 29-33 Ectos (same with the value of the ecto)
guilds are a more helpful and productive thing now in which other kinda runs that yield any payment or Fissure of Wow Armor/Chest or Underworld Run to chest(in which someone is just lazy and doesnt wanna run with a group)
So finding a farming build if gunna be the best case for you
FOW(Fissure of Wow) = Obsidian Shards (Another higher end selling thing but alot less value like 1/10th the value of ecto, but is used for the rarest armor (FOW armor)
UW(Underworld) = Ectos
So find a farming build based on what you need
http://gwpvx.gamepedia.com/?cookieSetup=trueGo to builds by profession and pick the profession you want and find a UW build and watch videos for it to learn how to do em to farm ectos
theres also event farmers which are Raptor/Vaettir Farmer in which are events you get event drops, meaning more monster kills more event jobs
some of which come very useful for your other farms and are easily sellable as well