A sunny balcony and the right climate are the essential things; that, and time. When to plant: Spring Soil and watering: ordinary potting soil; Keep the soil lightly moist. Care of the tree: pruning with caution for the first four years: remove branches under 3 feet. Plant hygiene: watch out for scale infestation, insects, ants and weeds.
Could you elaborate on the climate? As far as I am concerned sunny balcony or a garden or a terrace is easier obtained than actually correct weather conditions. It's a brilliant idea and I approve but I doubt I could do it in my place. Even if - somehow - I was able to have fruits on my tree, they wouldn't have the taste quality comparable to those from Mediterranean.
Superficial damage to olive trees begins when temperatures fall into the low 20s.
. . . Significant damage occurs by mid-teens.
. . . Single digit temperatures are fatal.
In areas colder than Zone 8 (10?F), Olive trees must be grown indoors during the winter.
. . . Choose a place for your Olive tree that receives full sun (at least 6 hours of direct sun each day).
. . . A location near a sunny, south-facing window is ideal.
. . . Take care to position your plant away from heat vents and radiators and not too close to a window,
. . . which can act as a magnifying glass and literally “fry” the leaves.