All you need to make extra money is an open mind, motivation, grit, and determination to use your creativity and skills you may already have or can grow.
Have an eye for fashion but still have tags on your clothes? There's a market for that. You can sell your unused clothes on several sites that may give you up to 80% of the cost of the item. Some will take a small commission.
There are expanding platforms to sell your professional services as freelancers. Among the places, you can list your services and bid for jobs are Fiverr, Upwork, and 99 Designs.
Like fiddling with computers and smartphones? You will be in demand by folks like me who don't know what is wrong with their electronics. This kind of work can be done locally on your schedule.
Are you handy with hands and have some flexibility? There is a task waiting for you on TaskRabbit, and they will pay you a generous hourly rate, depending on the job and location.