I know for a fact that some of these ways, and ideas have been posted before because i "have been leeching for 210 days" says the little box up there.
First off the most obvious, and posted spot to farm for herb if you have decent gear is the trees in skettis becasue you can herb them and get motes/herbs easily making much $$$$ per hour. This is what I do if the area is highly populated with peopel farming them.
If an opposing faction is killing the tree i wait in stealth outside the trees aoe range and in a non obvious spot, once the horde/alliance kills the tree i wait for them to loot ( i can tell this cause i mouse over the tree to see when the herb mouse comes up) after they loot i sap them and herb it. Usually the first time they will be surprised and youw ill get away free, if you are doing this to the horde multiple times tho be prepared for them to trnket out of the sap, which is when i use blind. Im sure this woudl work for other classes like mage can sheep, druids pounce, any time of CC.
The other way i make money with herb, and herb isnt required but i farm the herbs on netherwing ledge, they drop motes of mana, i also kill the nether rays which are never being farmed, and have a high drop rate of motes of mana. Basically no competition because everyone just wants to get their dailys done and will leave you alone.
GL with your money making, i did the first strat to get my epic mount, and now i use the 2nd strat when doing dailies and beoing bored.