Some Tips to Avoid Ponzi Schemes:

As with all investments, exercise due diligence in selecting investments and the people with whom you invest.
Make sure you fully understand the investment before you invest your money.

Some Tips to Avoid Pyramid Schemes:

Be wary of “opportunities” to invest your money in franchises or investments that require you to bring in subsequent investors to increase your profit or recoup your initial investment.
Independently verify the legitimacy of any franchise or investment before you invest.