you can set up a Nightmare Zone scenario where you can AFK train for 20 minutes at a time. Using an imbued magic shortbow and amethyst or rune arrows is the usual way to go. You'll also need some super ranging and absorption potions...
(you can buy at the Seers village pub for 20gp each), Axe, Pickaxe, Any ogre bow, Any ogre/brutal arrows, Iron spit (smith with an iron bar), Log, Tinderbox, Ogre bellows, Ball of wool, Pot of cream, Raw sweetcorn, Hatchet, Machete, Pot, Raw chicken, Dramen staff, Anti-dragon ...