Pick your fruit when it is black all over - try for windfalls under the tree.
Place the olives in a bucket or other container and cover with water.
Change the water every day for about ten days after which most of the bitterness should have gone.
Discard any which show bruises or blemishes.

Make up a brine in the ratio of 100 grammes salt to one litre of water.
Leave the olives soaking in the brine for another ten days.
Drain, pack into jars and add enough brine to come half-way up the olives.
Add the same amount of vinegar and top with good quality olive oil to seal off the top.