Other advice, from someone who has interviewed and been interviewed on Skype:
Take a really good, hard look at what's behind your chair. Once I had the embarrassing experience of being interviewed on Skype for a video YouTube piece and when I got to preview it for editing I saw my cat having a nice, thorough bath on the shelf behind me! (They didn't notice, but I called it to their attention, we all had a good laugh, and they blurred her out before it went up.)
Remove all clutter from behind you, including the stuff over the back of your chair. All of it. Move your computer to a place with a neutral background if you can't.
Dress as professionally as you would if you were sitting in the HR office. Small earrings, no bling, suit jacket.
Turn down the light in your screen as much as possible if you wear glasses, because the glare on the lenses will be blinding on the other end. If you don't wear glasses, check ahead to see what light level makes you look your best, not washed out or green or orange!
Set the little window that shows your face to you as close as possible to the camera, so when you look at yourself it looks like you are attending to the person on the other end.
Practice with a buddy ahead so you can get a critique of your presentation. I'd go with the smallest possible earbuds, buy some black ones, and put the wire behind your head so it's not a distraction to the viewers. The idea is to make it like a regular conversation, and how much to you like trying to talk to someone with headphones on? Would you wear headphones to a face-to-face interview? No, I didn't think so. Visual cues are important.