Here's a great article from cnbc on ways to earn extra money. This is a process that requires creativity and honesty. Creativity to see what is out there and honesty to know where you can compete and what you're good at. If you only took Spanish in high school. Don't try to be a translator.
Here are 10 extra good ideas. There are certain natural monopolies that play into your hand. If you want to mow your neighbor's lawn than there probably won't be anybody who can do it cheaper. Be the closest driver when it comes to Uber, etc. These require little to no skill, they're just commodity businesses. Regardless, you can make some good money at them!