Go to Port Sarim, west of Draynor village, and ask one of the people in the blue uniforms to go to Karamja and pay them 30 GP. When you get there, walk off the dock and you should see a house. Enter the house and talk to a man named Luthas. He will ask you to pick bananas. Answer "Yes", pick bananas, put them in the crate, then talk to Luthas to collect your moderately earned 30 GP. If you would like more money in multiples of 30, ask him to get another 30 GP for doing the job again. Stay here for a long time if you need to spend several thousand on items.

Get your character's mining level up to level 38 by mining iron, etc. Then, go to the Barbarian Village and mine coal from the rocks, which you can sell for 100 to 300 GP per piece. You will also occasionally find a gem (from least valuable to most, sapphire, emerald, ruby, diamond) which can be sold for good prices.

Once you are at level 40 mining, add a person named yodoo86 to your list. He always buys coal. Mine coal and sell to him for 100 GP.

Get your smithing and mining levels up to 40 and mine gold in the Lessers Pits on Karajama Island. However, be careful of the level 21 skeletons. There are five rocks, so on a good night when no one is on, you can hit them in a row making your trip very easy. You can usually get 25 gold ore that becomes 25 gold bars. Put them into certs and sell for 1k a gold cert.

Mine and smith until you are at level 20 at both. Make Bronze Bars and turn them into things at an Anvil such as: a 2-H, Mail Plate Body, Skirt, or Kite Shield and sell them at the market for good prices. You can also do this with Mithril, Runite (not Rune), Adamantite, Iron, and Steel.

Go to the house outside of Lumbridge and collect Iron Daggers on World 13. Also, defeat Goblins for items that can be sold or gold, which is common. Sell the daggers for 14 gold or less at the market.

Enter "Moneybags" on your friends list. If you catch him while he is on, he will give 1 to 900,000 GP.