Sunlight - Fruit needs plenty of sun, whether it ripens on a branch or bramble.
Soil - Almost all the fruits do best in a slightly acidic soil, somewhere between a pH of 5.5 and 6.5. The exception is blueberries, which prefer a soil of even greater acidity (pH between 4.0 and 5.0).
Drainage - Whatever fruit you plan to grow, adequate drainage is important. When scouting the backyard for a suitable site, avoid low-lying areas that collect water or are slow to drain in the spring.
Pollination - Most fruit trees have both male and female organs in the same flower, but not all are self-pollinating (fertilized by their own pollen). The best bet is to have more than a single variety within 100 feet, so bees can travel between and cross-pollination can take place. Small fruits, except for blueberries, can be fertilized by their own pollen.