a primer on approaching cats and people you don't know

Make eye contact and acknowledge the other party's presence.
Approach slowly, travelling nearly all of the way
but stopping just short of them. Establish,
between the two of you, a comfortable distance
and then demonstrate by whatever means necessary
that you mean them no harm. Kneel if you have to.
Be patient and wait for them to either advance or retreat -
bearing in mind that now might not be an especially good time.
But - if the other party does eventually decide
to reciprocate, as far as it depends on you,
be polite and try not to rub them the wrong way