I'll admit that I've got a bit lazy with my interview audio quality, focusing more on content than on fixing all those little audio glitches that happen during an interview. However, I learned at least three things I didn't know that I suspect will greatly improve the audio quality of my interviews from this in-depth video on recording Skype calls by Doug Kaye and Paul Figgiani. Even if the bulk of the content is too technical for you, you should listen to the first five minutes to hear the difference in audio quality between a microphoned Skype caller and a telephone callee.
I learned far more than I thought I would, and hey, I even skipped the part about reconfiguring my firewall. I highly recommend this if you want to improve the quality of your Skype interview recordings!