Things I wish graduate advisors had told their students about doing Skype interviews.
Do *not* sit in front of a window, door, or any other place that will let light in behind you. Most curtains are not sufficient to make up for being in front of a window.
Do have a light in front of you so that we can see your face. When you are wreathed in shadow, you look like a supervillain making a ransom demand. Practice talking normally while a bright light is shining in your face. It will help with Skype interviews and if you ever find yourself in a film noir police station.
Make sure that your camera is at or higher than your face. Being shot from below is not a flattering look for anyone, and seeing your ceiling behind your face just looks weird. Stack books under your laptop or smartphone to make this happen.
If you are using a smartphone, make sure it is horizontal, not vertical. If your interview committee is using a laptop, it is almost certain to be horizontal.
If you are interviewing in front of a door, close it. (We don't really want to see your laundry room behind you during the interview).
If you can, use a headset with microphone attached to prevent feedback and for better audio. Test your setup beforehand to make sure it is working!
Plan to do the interview from somewhere you know you have a solid Internet connection. If you have to switch to a phone or delay the interview, you might not get a second chance to interview depending on timing.
If possible, use a laptop rather than a smartphone. Laptops tend to have bigger screens, you don't have to be constantly moving your head super close to the phone to see your interviewer.
Clean your camera before the interview. Hopefully with a microfiber cloth, but a quick wipe with a cotton cloth will do in a pinch.
If you talk with your hands (like I do) try not to put them between yourself and the camera lens. Seeing a giant hand coming at the interview committee can be distracting. Sitting back from the screen somewhat can make this easier.
(Advanced Technique) Practice centering your eyes on the camera rather than at the middle of your screen. That makes you look like you are looking outward from the screen rather than avoiding the eyes of your interviews. Again putting some distance between you and the screen will make this much easier.
Sadly, all of these did happen during the interviews I did over the last three days. On the other hand, there were a handful of interviews that followed all of these rules, and it did make their interviews stand out.