I was asked a lot of general questions in my interviews such as:
Explain the differences between shapefiles and geodatabases?
What is a domain?
What is the difference between vector and raster data?
What are the basic elements that should be on a printed map?
Here are some more general questions. learning resources - General GIS Questions for Job interviews - Geographic Information Systems Stack...
As referenced above, be professional, dress professional, be attentive. Smile during your interview. Emphasize your strengths and tell them you are working hard to fix areas that you consider weaknesses.
Make sure your Skype is working correctly. Make some test calls to friends to test sound and microphone.
Good Luck!
Steven