Whatever comes to you, the first thing you should do is not the allow that thing to cause panic in you, or in fact, let any sentient thoughts arise in you. To do that, chanting is a good practice.
If I were to meet ghosts again, I will chant Namo Ksitigarbha Bodhisattva (na mo di zhang wang pusa). There are also some powerful mantras against evil spirits, but usually to chant them you must have the right knowledge and right views to use these mantras. Perhaps Origami can tell you a bit more?
However, if a ghost really wants to harm you with great hatred, chanting may not be enough in long term... you must seek help from a monk/guru/etc... even seek forgiveness from your "creditors" of previous lives. I don't know what exactly will be done.
Ghosts, don't bother about them, "xin li mei you gui", usually they won't find you
