Do a test call with a mate and ensure there are no connectivity issues on your side. Get the use of a decent headset if possible.
Get familiar with the skype functionality. Can you present your desktop? They might ask you to run through your CV and if you show the ability to present comfortably etc then its all bonus points.
A silent area, free from any disturbances during the call.
Do it on a connection with no contention issues.
Also google ‘skype interview posture’ and brush up the finer details.
sure you knew all this already