Legitimate paid surveys are a great way to earn money. Some of them pay in cash and some pay in rewards. The amounts paid by survey sites are typically based on the amount of time and the complexity of each survey.
For legitimate survey sites, a good rule of thumb is to avoid survey sites that charge you to sign up and get paid for surveys. You can rest assured you are not being scammed if the site is free to join and take surveys.
There are so many survey sites out there that it can take a long time to figure out which ones actually pay you for your opinions. I am an active member of all of the legitimate survey sites I have listed below and I receive regular payments from them with consistent survey offerings, and best of all they are absolutely free to join. You should never have to pay to get paid!