Professional lighting on the cheap for Skype interviews:
Change your computer background to a nice amber/orange color so your face looks warm and isn't washed out by the blue LED backlight. Get a lamp, take the lamp shade off, and position it to your left (about 10 o'clock position) and about three feet away - a 40-60 watt bulb is best for this. Turn on the overhead light in the room you're in (it will act as a "hair light" (technical term) and illuminate the top of your head with some shine to give depth). Then get a floor lamp (or put it on a shelf or something) with, preferably, a brighter bulb than the lamp on your desk (75 watts is good). Place it in the 4 or 5 o'clock position, about 5 feet away from where you are seated. For the best effect, place a white poster board or sheet behind the lamp pointed towards the back right of your head.
If you can do this setup in a room with window (covered w/ blinds or a light curtain) that is even better. Set it up so the window is to the right of you. This will give a pleasing contrast, as the lamp to your left will read on screen as a warm color, and the window will read as a cool color. This provides good definition to your face and is a pleasing set up. It is also important to only use one "type" of light in the room. By that I mean, mixing fluorescent with regular tungsten bulbs will cause color issues, as Skype cannot set the white balance properly. I would recommend using all tungsten (or "warm" CFL's) bulbs, plus the window, and you will get a nice contrast but proper color.
Keep your chin slightly up, with your face turned just ever so slightly to the right. But then relax and be natural
. You should always have a slight smile, and you should appear engaged, happy, enthusiastic, etc.
Also - make sure your background is free of clutter. This is very important. A simple, clean room as a backdrop is best. And by setting up the lighting as described above, the room will appear slightly dimmer than you, making you the part that stands out, and causing the background to be less distracting.
Finally, feel free to experiment! All rooms are different. Go to the preferences of Skype and you can see how you will appear. Play around with the angle and distance of the lights until it looks good to you.