We recommend using a digital recorder. These come in many different forms—such as dedicated piece recording technology or a program installed on your computer, phone, or tablet with a microphone. No matter what type of digital recorder you use, it should ideally have:
For interviews, it is often a good idea to have an interview agreement with the person(s) you are interviewing.
1) In some locations, it is actually illegal to interview someone without written consent.
2) Written consent establishes another piece of evidence that the interview itself actually occurred when you state it occurred.
Note: It is also a good idea to state during the interview itself when you are interviewing, who you are interviewing, and that you have been given consent for the interviewee. Example: "It is [date]. I am here with [interviewee's name] who has given consent for this interview."