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.
Have a yard sale to sell things you no longer need. Choose a day or a couple of days to have your yard sale. Advertise it in your local paper and online, such as on social media and classified websites. Then, on the day of the sale, arrange the items on tables, blankets, shelves, or in other ways in front of your home. You can arrange the items into groups by price, or price them individually.