Only invest in schemes that have a clear plan for paying off the pyramid scheme's investors. Duh.
Example: If you're selling "Get Rich Quick" pyramid scheme, make sure you have a plan for how you'll pay off the people at the top. Like, actually have the cash stashed away in a Swiss bank account or something.
Or, you know, just make up some nonsense about "dividend payments" and "returns on investment" and hope no one asks too many questions.