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...
ammonite crabs, or the nightmare zone. In that case, consider gaining some Slayer points fast by taking 9 consecutive tasks from Turael and switching to Konar for each 10th task.