There are some methods. Fastest one's paid for, but there are some free. Don't expect more than 2m/h for a free one. These should be in the Guides section.
Like Hey-Jason said, the most common way is junk trading as you can't get banned for it since it is just an honest trade in the eyes of Jagex. There are other ways but your best bet is to stick to junk trading as it's the safest and most reliable.