If you've got 90+ attack and strength, then melee would be better. Ranged installment though would go something like that... Method - Stand straight in front of them, shield melee and use eagle eye. They will hopefully melee the majority of OSRS gold the time, along with your d'hide / arma will tank nearly all of their magical strikes. The only damage you'll take largely is that their ranged attacks.
I think, to begin with, you need to build a living area, and construct a floor in the center of it and construct an oubliette room beneath it. In addition, you will need to construct a trap door in there. Following that, there are two other ways of getting into it: A big cave entrance that you build in a garden/fancy garden. A flight of stairs in a space.
After building one of these two you have the option to construct a space below, and there should only be one choice for that. After you construct those room(s), you are able to build normally in building style, construction treasure rooms, dungeon corridors and junctions, or some other room from above that you want to get down below too.
Also, if you haven't already, doing the Love Story pursuit unlocks a new kind of dungeon room which adds a whole multitude of new dungeon guards that you can add down there, like scarabites, black demons, iron paintings etc., and cheap RuneScape gold nearly all of these new creatures are cheaper than the initial trolls, hellhounds and metal dragons etc..