Rune chain, granite legs, d med and whip is what i use. Just use protect-item prayer if a pker comes to you. Plus, bring lobbies, and a teletab or tele runes.
If you want to spend ~1m, but want it fast, then do Fally Teles. If you are a member, do Cammy teles from 45-55. Or, if you have a low budget, do fire strikes/bolts or curses on the monk of zammy in varrock castle.
I suggest getting 40 defence and attack first. At that level, it would be best just to get rune. Also, try not to do pest control at such low a level. You will get called a noob and will barely kill anything. You need 40 combat for pc.
If you are not a member, then look at the forums and see the cheapest person selling coal. Or, you could go to world 1 fally, there are lots of people selling coal cheaply there.