See Ammunition
See Alchemy for oil recipes.
whittle + wrapped = 50 heads
Bundle of heads + bundle of shafts = 250 arrows
Recipes
Arrow Head type + Bloodseeker Oil = Greater Arrow Heads
Quicksilver = Bloodseeker Oil
Arrow Head type + Elemental Oil = Elemental Arrow Heads
Brimstone = Acid Turpeth = Fire Colcothar = Frost Cobalt = Lightning
Greater Arrow head of any type + Elemental Oil = Greater Arrow Heads
You can't increase the damage of elemental arrows by using a higher damage arrow type like armor piercing. It's best to use regular arrow heads for this.
Greater Arrow heads + Bloodhunter Oil = Deadly Arrow Heads
Stibnite = Bloodhunter Oil
Greater Elemental Arrow Heads + Bloodhunter Oil = Deadly Elemental Arrow Heads