Simple answer: A device to record on and a quiet space. Best practice is to use a quality microphone and a computer with simple audio software. *We do not recommend using phones or tablets with their built-in microphones.
Long answer: This is a complex question and if you ask ten people you might get ten answers. You can invest in expensive microphones, audio interfaces, audio software and treatment for a permanent recording space. But be very careful not to spend too much too soon. We have helped many podcasters setup home and remote studios on almost every budget size. We are happy to help you get going too. CONTACT us anytime.