Alright, I'm going to run through where & how I am going to kill the creatures effectively:
Range around Karamja volcano. There are 5 spawns here, and they are not too spread out.
Probably Goblin Village, as there are a lot of goblins here. Ranging will probably be quickest, although using the free to cast mage spell is an alternative.
Probably the 4th level of the Stronghold of Security, using melee. Although they will be slower to kill, it is one of the few places where there are significant amounts. However, I will look into other places with weaker skeletons.
Use Armoured Zombies, which I can probably tank. These are good melee xp, and are afk, which is very good.
The area with snape grass spawns has a fair amount of them, very concentrated, so would be good for obtaining a scroll.
Edgeville dungeon has a lot of hill giants, and should be quiet on a P2P world, and easy to complete.
Ground floor of the slayer tower, as they are weak and easy to kill.
Earth Warrior Champion
Aberrant Spectre Champion
Lesser Demon Champion