If you haven't already it's best to start by offering a trading idea or building a strategy. The former is perhaps the easiest to do.
Offering a Trading Idea
After you have published a few Trading Ideas you will probably be ready to step up to building a trading strategy.
Trading Strategies is where the real money is earned as part of a 50:50 revenue share with Zignals (once out of Beta)! After attracting some followers with your Twitter account you will also have a ready made market to sell too.
 I won't go into the details of how to build a strategy, other than direct to previous posts on the subject, here and here with a downloadable PDF here.