I think slayer is a great way. I would perm cancel: black demons, steel dragons, ice wyverns, and any other task you hate a lot.
Slayer = 1) a way to not get bored while training.
2) a method to acquire charms without becoming overly bored
3) a way to get tons of treasure trail items from clues
4) tons of herb drops for herblore lvling
5) lots of cash on monster drops (especially at higher lvls)
-still good cash at lower lvls, just pick up herbs, runes, etc.
6) just a fun skill to lvl!