Position your subject in a chair, preferably against a backdrop with some visual interest, but not so much interest or complexity that it distracts the viewer.
Position the interviewer in a chair 2-3 feet in front of the subject if the interview is going to be part of the video.
Position the lighting. The strongest light source, also called the "key light," should fall on the subject's face, not straight into her face but from a slight angle and from slightly above her line of sight. Key light may come from a window or artificial source, but light diffused by curtains or other filtering looks better than hard, direct light. If possible, position another, weaker light source so that it partially fills the shadows created by the key light.
Position the microphone and connect the microphone cable to the camera. A lapel microphone attaches to the subject's collar or under her shirt and is usually the best option. A shotgun microphone mounts on a boom and is held directly over the subject's head. Shotgun microphones have narrow pick-up patterns and will only "hear" sound directly in front of the microphone, so position the microphone carefully.
Place the camera on the tripod and position it in front of the subject. The camera should be placed on the same side of the subject as the key light and at a distance to allow either a medium shot, which shows the subject from the waist up, or a medium-close shot, which frames the subject's shoulders and head. When composing the shot, leave some "nose room" in the direction the subject is looking. If you want, place the interviewer so her shoulder is in the corner of the shot, creating an "over-the-shoulder" effect.
Check the sound. Viewers are less tolerant of bad sound than bad visuals, so the effort to capture good sound is worth a little extra time. Check your microphone connections, plug in the headphones, turn on the camera, and have your subject speak in a normal tone so you can hear the audio levels. Adjust the microphone so that it is not picking up extraneous sounds. If necessary, move the microphone so the subject's voice is clear but not overly loud.
Press record and conduct the interview. Make sure the tape or card is in the camera. The subject should talk to the interviewer, not the camera.
Record nod shots and B-roll. If your interviewer is positioned in the shot, you will want to move the camera and lights, if necessary, to record a series of reaction shots, also called nod shots, of the interviewer. When you edit the interview, use nod shots to create visual interest and build transitions between questions. You might want to shoot some B-roll, such as close-ups of your subject's hands or any props they referred to, as well as wider shots--"establishing shots"--that show the interviewer and/or subject in their surroundings.