FlexJobs is 100% legit. While it may not be necessary for everyone, if you have limited time available to dig around on the internet and vet companies for legitimacy it’s well worth the investment. They research each job lead to make sure it is truly remote or flexible and it isn’t a scam. I’ve had a membership for a very long time and find it well worth the small investment.
Drive for Uber or Lyft: If you're in a locale where you can find Uber or Lyft (or even one of the many competitors around the world such as China's Didi), you could easily make a respectable income. The hours are flexible and you can work as you see fit, making it perfect even if you currently have full-time employment but are looking to make some money on the side.
Once you have that problem or need nailed, the next step is to validate that idea and make sure you’ve actually got customers who will pay for it. This means building a minimum viable product, getting objective feedback from real customers, incorporating updates, testing the market for demand, and getting pricing feedback to ensure there’s enough of a margin between your costs and what consumers are willing to pay.
Whether you have a website or are still dreaming up ideas for a blog, you can also look into affiliate marketing. With affiliate marketing, you partner with brands and businesses within the content of your website. If you mention a product or service, you link to that produce or service using a unique affiliate code you received when you signed up for that particular affiliate program. From there, you’ll make money any time someone buys a product or service through your link.