Should I suggest the following;
- Luring them Properly
Take your time into managing between Italy Rock and the Northern Square Shape Rock.
Sometimes it's worth taking a Stamina Potion to help you with the Running Around to Lure other than a Brew/Pray pot.
- Assigning Priority
No matter how much Range Defence you've got, always get those Rangers out of the Way.
Be Intelligent with how you do it tho, as it could lead you into getting melee smacked big time (360/180s)
- Prayer Flicking
Even if you suck at this, at least try to do it with your Range Boosting Prayer (Eagle Eye or Worse).... Should save you some prayer points unlike leaving it on at all times.
Should you need more help feel free buddy
Or perhaps a Cheap firecape Service