I'm not very experienced with RS gold the money-making of members so here are some freeplay items. Kill Hill Giants are found in Edgeville's resource lair. Take bones as well as limpwurt roots. ~250k gp/hr last Summer. It is best to only purchase the most valuable items (no pizzas with anchovies). This is the best opportunity to earn money through F2P. If you're lucky enough, the payout could be as high as 400k/hr. However it may take some time to buy.
Mine adamant ore. This is my preferred way to go. Wear full batwing, shield, and food will not be needed. Hop worlds. The PKers here are so rare you don't even need to think about it. If you'd like to prolong your travels, you can superheat coal mines. However, I am not sure if this will be more effective. 70 mining buy OSRS gold required 70 smithing, if you are superheating. 200-300k gp/hr.