I'm a causal player, which means I don't really care about xp/hr or gp/hr, I prefer afk style training, and I want get every task done as fast as I can. I always get task from Morvran, the elf. Remember to carry slayer VIP ticket when getting a new task. I always choose regular task over slayer challenge. I solo most of the time, although you might want try co-op if you can. Mighty slayer helmet is a must, get this. Get all the slayer items on tool belt. Turn on the slayer counter.
The fastest way is use Tirannwn quiver 4 teleport to Harmony pillars; or use Crystal teleport seed teleport to Meilyr Clan. These creatures drops Blood necklace shard. Sometimes a elite one will appear, it's better duo with others, otherwise avoid it. Wear the best melee weapon and armor, pray deflect magic or soul split if needed, summon Steel Titan. Bring infernal urn if you wish to train prayer, each urn will hold 18 tortured ashes. It's safe to tank 3 at once.
The fastest way to get there is Hoardstalker ring teleport. Wear your best melee weapon and armor. Because these creatures have high defense, Turmoil prayer and Scrimshaw of attack are useful. Bring 3 overload, 5 prayer flask, 4 adrenaline flask; Bring Dreadnip, it could be very useful. Bring healing e.g. Excalibur, good quality food Bring 1 Portent of life or death, and 1 house tab, just in case you are low health. Don't need to worry its special, just tank it, soul split if neede