If you’ve got expertise in a certain area, package up your knowledge into an online course and sell it. This has become a very popular business model for online entrepreneurs over the past several years. The two big websites that are used to sell online courses are Udemy and Teachable. Check out this awesome article by Regina on How to Create an Online Course that Sells.
Become an Amazon Associate and then use Keyword planner to find an in-demand niche: With more than a million different products to choose from and up to 10% commission the sales you drive, Amazon’s affiliate program is a great place to get started. Browse their available products and see what connects with you. Or take it a step further and use Google’s Keyword Planner to quickly check how many people are searching for a specific term. With affiliate marketing, the more relevant traffic you can pull in, the more you’ll make off your site.
People are always looking to have their cars washed and detailed. You could be a mobile car washer and detailer without having a permanent location. Reach out to people you know or make some flyers and put it in your neighbors' mailboxes. If you want to get serious about it, prop up a one-page website or give out business cards. You can make money quickly doing this.