kitsuneae: Never pull a cat's tail.
Why? They like that, if they are familiar with you and they trust you. The best proof/test of the ultimate human <-> cat bond is this: nab, pull, squeeze their tail softly and see how they react. If they purr, meow, rub their cheecks against your hand, press their backbone upwards in a reverse U shape, or even better start chasing after goofily/merrily their own tail in a circular fashion, then you are their best buddy.
Back on topic:
Never give catnip to cats (they won't eat it; instead, make a herbal tea for you out of it)!
Secret tip: fondling the tip of their tail makes them assume funny facial expressions and become ultra playful, towards you