The Brokers need to be credible and have a history of success. Some Brokers can source a large number of investors at one time ,while others can only source a couple of investors at a time. The first step is to retain an experienced EB5 attorney such as our Law firm, who has the connections with the credible Brokers and can assist you with their marketing of your project to the investors.
Looking at a concrete history of I-526 filings and approvals would be a good start. Face-to-face meetings are also very helpful, and any background research and due diligence you can perform on the legitimacy of the business or law firm will benefit you further.