To start with, test the profit of making one headless arrow - buy one feather and one arrow shaft from the Grand Exchange, make a headless arrow, and sell it. If the profit is less than 10, there may be better options to make money. If it is higher, buy up feathers and arrow shafts in bulk.
To create headless arrows, use the feathers on the arrow shafts. A menu will open asking how many you want to make; click all, which will make 10 sets of 15 headless arrows. Each set of 150 takes about 12 seconds, so you can make more than 40, 000 headless arrows per hour if you have enough materials. However, feathers have a buying limit of 10, 000 every four hours, while arrow shafts have a buying limit of 20, 000 every four hours, so you can only buy about 15 minutes worth of headless arrow materials per four hours. It may be useful to put in an overnight offer for feathers and arrow shafts if you have enough money to start with. You can buy more feathers at fishing shops (around 1, 000 per 24 hours per shop).Because making headless arrows does not require banking and only takes up three inventory spaces, it can be used in conjunction with other moneymaking methods where there is a long wait between actions. This includes collecting cave nightshade, cave goblin wire, and potato cactus. For F2P players, Grapes (1, 874 ) at the cooks guild or Red spiders eggs (1, 661) in the Varrock Sewers can be good. Feathers have 10, 000 buy limit and arrow shafts have a 20, 000 buy limit.