The best tactic is to develop your own custom list and update it frequently. Check newspapers and magazines, including small or local publications for the names of reporters who cover topics similar to yours. Watch TV and listen to the radio, and note the reporters and anchors who might be likely to use your stories. General contact information is available in departmental sections of the newspaper. For broadcast outlets check the phone book.
Libraries have media directories, and larger media outlets can be searched online.
Your list will probably include newspapers, TV and radio stations, magazines and trade journals, and possibly wire services. Contact each outlet by phone, email, or in person, to ask how and when they would like to receive information from you. Media personnel change regularly, so it's best to update your list at least every six months.