Making a Living
Most urban homesteaders need to generate a cash income in addition to their homesteading work. Urban homesteaders generally have less land to work with and more restrictions to deal with than rural homesteaders. However, there are likely to be more sources of regular jobs nearby. You might also be able to find a way to create a cash income by taking something you love and creating a service or product around that.
You're likely to have zoning issues to contend with as an urban homesteader, so do some research about your local laws and licensing requirements before investing too heavily in some idea.
Crafts
Many people find they can take a hobby, such as making wreaths, signs, dolls, wall decor, garden sculpture or other crafts, and earn a supplemental income by selling to retail shops. You might also explore the idea of selling at craft shows, but if they take too much time away from your homestead, you'll need to figure out someone else to do the chores while you're gone! Selling crafts that are holiday-themed are a perennial favorite. If you like to garden (see below), consider using your own herbs in sachets, scented oils, soaps, and other items.
Food Ideas
Depending on your local zoning laws, you might be able to sell the extra produce from your garden, make specialty jams and jellies, or sell baked items.
Plants
If gardening is your thing, explore the possibility of selling your own plants you raise from seed or by transplanting. People often like to buy from local sources so they can be assured the varieties will do well in their own home. Some farmer's markets will allow plant sales. Herbs and flowers are always popular, but consider starting popular vegetables from seed and selling those as well. Both fresh and dried herbs are popular for cooking and crafts.
Firewood
If you have a source of wood, a chainsaw and a pickup truck can put you in the firewood business.
Hunting and Fishing Guides and Teachers
If hunting and fishing is your thing, look into what it takes to become a guide or teach classes. Even in the midst of urban development, there are lots of people who enjoy fishing or think they might like to learn.
Computer Setup and Training
If you're handy with computers and comfortable learning new things, you can make a good living with flexible hours as the local go traveling computer help. Train people on popular new programs, help them set up new computers and install software, set up new email accounts, and install anti-virus software. Offering to make house calls is a nice service.
Housecleaning or Janitorial Services
Another option when you want to work part time is to become a housecleaner. You can work with a local service or set up your own operations. With so many two-income families these days, many will jump at the chance to have their house cleaned while they're gone. Office cleaning is mainly done at night so this is a good option for those looking for evening work.
Ease into Your New Business
Whichever sideline you decide to go after, consider easing into it with as little cash outlay as possible while you see whether there's a market for your skills or not. Advertise locally and tell everyone you know about your new venture. Do up some simple flyers for your services and post them where allowed.