Everyday, Zaff found in Varrock will sell RS gold players underpriced battlestaves, with their prices increasing according to Varrock Diary quest progression, that results in an extraordinary huge effective gold per hour rate. It's like printing money, please Do it.
After you've completed Gertrude's Cat quest, she can be your Gertrude will gift you adorable kittens. There are no charges or questions asked. There are no conditions required. Every kitten takes three hours to mature, then it's time to exchange to Gertrude in exchange for either 100 Runes or 200 after completing Ardougne Diary (easy), which seems insane, but is actually the case. It is possible to keep mature cats in your bank and have them turned in all at once to make it easier for you.
Skill up Cooking skill level to 29. After you've picked the cooking up, collect two packages that contain "the stuff" (reward of Trouble Brewing minigame), four buckets of water four bushels barley malt two ale yeast kettles eight pinches of buy Runescape gold harrarlander as well as sixteen beer glasses empty. Then walk up to the top floor of Laughing Miner Pub where brewery is located.