Backyard homesteading is done on a fairly small piece of land, usually the size of a suburban backyard, while still achieving the same goals of self-reliancy and sustainability. Even just an acre of land can feed a whole family while also supporting a few animals. Greenhouses are popular options within backyard homesteading, thanks to their affordability, flexibility, and their gigantic benefits. Greenhouses are a beautiful addition that provide a safe, healthy place for plants to grow and thrive. They can fit almost any budget, and subsequently come in a wide variety of sizes and designs. You can grow specific crops and varieties that are suited to your family's pallate, and you'll know exactly what is going in to their production.
Urban homesteading, or backyard homesteading, will have to contend much more with local ordinances and HOA agreements. This may make growing some food, or especially raising animals, more difficult. Do some research on your area and what the rules are, how can you work around them? While cows and chickens may be out of the picture, what about bees, rabbits, or fish?