General Method Description

Chaos druids are the best herb droppers in the game, and also provide runes, mithril bolts and herbs as occasional drops.

At level 30 a good place to fight them is at Taverley Dungeon. Even at low levels no food is needed for these.

Once you have level 46 Thieving you can picklock the door to the famous "blood rune tower" just north of Ardougne. It is less crowded than Taverley and closer to a bank (use the log to cross the river for banking.)

Once you have level 82 Thieving you can open the shortcut between Yanille and the Agility Dungeon, giving you access to the closest chaos druids to a bank in the game. You need a lockpick to open the door going into the dungeon; just drop it each time and get a new one for the next trip. You don't need it to exit to Yanille.

With monsters that drop a large number of herbs, there are trade-offs between keeping all the herbs or leaving the lower-valued ones so you can try to get more of the ones that cost more. There is also a trade-off between using a beast of burden to get more herbs per trip, or summoning a macaw for its herb enhancing benefit, because the macaw increases the percentage of good herbs (ranarr and above) by a hefty 40%. The key factors that determine the best approach are the number of herbs you get per hour from the monster, the distance to the bank (and thus how much time you waste per hour banking if you take more trips) and the value of non-herb drops.

Chaos druids drop many herbs, offer few items of value other than herbs, and are close to a bank. Thus, for these monsters, the best solution from a moneymaking perspective is to use a macaw and bank all of the herbs you get. At high levels you do more banking, but the bank is very close; at low levels the bank is further but you get fewer drops anyway.