If a stranger tried to make an unauthorized purchase with my credit card number, what else should i do besides cancelling the card?

i got a call today from Chase Fraud Unit. Someone tried to make an internet purchase with my credit card. it was for about $450. The purchase did not go through because fortunately Chase realized i don’t use the card much. They could not tell me much other than the attempted amount and the internet site.

what else can i do to protect myself beside canceling that card and checking my other cards to make sure no purchases were made with them? this information was unsettling, but i am happy they caught it. i am feeling unsettled because i’m not sure how this person, whoever it was, got my card number.