Your first 10,000
After you finish the tutorials, head straight to attacking chickens. Collect all feathers until you have 1 k feathers. Go to Varrock and sell them for 10 gp each (note you must be a member to do this).
Your first 100,000
To do this I would highly recommend you finish the Al-Kariad quest. Keep attacking cows collecting their hide, running to Al-Kariad, and banking your hides. After you get 1 k go to Al-Kariad bank and sell them for 100 gp each.
Your first 1,000,000
There are a number of ways you can do this:
Keep working on fishing until you can fish lobsters. Now if you're a member go to Catherby. If you a free person go to Karaminjar, and make multiple trips. Anyway keep fishing until you have 4 k lobsters. Sell the lobster in Varrock for 250-300 gp each and that should earn you roughly 1 million gp. This method is highly recommend as the need for food is great when you train and as you get higher in level.
