Olives are harvested when they change color, darken and indicate that are ripe. Do not let soften too much or be passed and fall from the tree!
It is said to have to collect on old moon (before the new moon) not wilted when we pay.
As the olives are harvested? This is the big question ... is unthinkable collect them one at a time, as we'd spend days. The form used for centuries, and why we chose is: a network / mesh fabric on the floor of the particular tree or branch that pick is placed; then they shake strongly (we can also hit with a broomstick) branches for the olives to come off and fall into the mesh.
Too much force will cause the olives go out and the tree suffers excessively. If you see that the olives are not easily detached, it is they are still green, leave more than a week and try again.
Once collected all the olives, it will have to spend some time out leaves and twigs, and passing a water (with the hose itself) to clean dirt and dust.