Mine adamant ore. I love to RS gold do this at the hobgoblin mining site. You can wear your batwing in full with shield, and you won't have to consume food. Hop worlds. The PKers here are so rare that you don't even want to consider them. Superheating can also be done through mining coal. This can prolong your travel time however I'm not convinced that it's better. 70 mining required, 70 smithing if superheating. 200-300k gp/hr.

Take on larger demons in the Forinthry Dungeon, use rune Arrows. It is the best range in xp for free players and offers 100k gp/hr. Multicombat allows you to swiftly kill the next demon. Air runes are around 200k/hr at the runecraft 66. The greater the speed the more efficient.

Mining rune. Because of the drastically decreased number of f2p universes, I have not done this in several decades. I mined rune around one month ago in the lava maze sometimes jumping to F2P worlds and around half of buy OSRS gold the f2p worlds had pkers sitting there. It's a bit of a pain too since there is no kbd lair so you have the option of killing them (doable if you are early in the journey), dying or running the entire way to 20 in the wilderness. The resource building dungeon of the mining guild packed with competitors, however it can be more rewarding than the wilderness. There are a few I may have missed. I had a long list that I posted somewhere, but it was the month of June in last year's.