I make over $2,500 a month from focus groups. Here's how I decide which ones are worth my time and how to find the highest-paying ones.

By Jane Zhang for Business Insider 

This as-told-to essay is based on a conversation with Filipe, a 30-year-old who goes by only his first name online and who runs his own business, One Click Hustle. Business Insider has verified his identity and income. The following has been edited for length and clarity.