Consider the promotion carefully. If it claims buyers can earn a certain income, the promoter also must give the number and the percentage of previous purchasers who earned that much. If the promotion makes an earnings claim - but the additional information isn't there - the business opportunity seller may well be violating the law.
Learn the disclosure documents. Under the Business Opportunity Rule, which is enforced by the FTC, many business opportunity promoters are required to provide a document to potential purchasers that include information about cancellation and refund policies, make sure the seller hasnt faced any lawsuits from purchasers or other legal actions alleging fraud, and contact information for references who have bought the opportunity.
Talk to previous buyers in person. This will help to reduce the chance of being misled by phony references.
Please do a few internet searches by entering the company name, or the name of the company’s CEO or president, and words like “complaints” or “scam.” Contact the state Attorney General's office, local consumer protection agency, and Better Business Bureau, both where the business opportunity promoter is based and where you live, to see if complaints are on file. While a complaint record may indicate questionable business practices, just because there are no complaints doesn't necessarily mean the company–or the opportunity–is legitimate. Unscrupulous dealers often change names and locations to hide a history of complaints.
Last but not least you may want to consult an attorney, accountant, or another business advisor before you put any money down or sign any papers. Entering into a business opportunity can be very costly, so it's best to have an expert check out the contract first.
