Secrets earning from twitter

We know that Twitter is a very good social networking site like Myspace and Orkut but from twitter we can earn a lot, just by posting ads in that site.The main secrets is to just collect some more and more followers in your twitter account.But yes there are some rules to be followed and one important rule is to post real ads after five ordinary ads .I just joined in a week and earned some $20from the site.Its a very good site to hang out with friends .