First Combat Method of Making money in runescape is Fighting Hill Giants . It is located west of the Cooks' Guild. and Southwest of the Grand Exchange. Fighting Hill Giant's gets you bones which sell for 332 gp each. So you get 9k Per Inventory, Depending on your combat level, you'll get about an inventory every 3 - 5 Minutes. So on average, you'll make 135k per hour.
To Enter the Hill Giant's Dungeon, you'll need to buy a Brass Key at the Grand Exchange for 700 gp. It is recommended that you start fighting hill giant's when your Attack, Defence, and Strength are at least 32 - 35+. If you have 22 Dungeoneering, you can go to the lair with even more hill giants, and you gain 15k Dungeoneering exp for entering for the first time. There is a limpwurt root respawn area there, so you can just pick them up, limpwurt roots are about 852 gp each. 23k per Inventory, 138k per hour.
You can also fight Moss Giants located in the Palace Sewer of Varrock for the same results, and fight Palace Guards for Grapes and sell to Grand Exchange for roughly 800gp each.