They should give you their username or ask you for yours so you can be on each others contact list.
Make sure in advance that your equipment is all working: Test your video settings and microphone by video calling a friend and checking they can hear and see you ok.
Make sure you're in an area which is quiet and you won't be disturbed. Don't be lax, make sure you follow the same procedures as at a traditional interview....switch off your phone etc. I don't see a need to dress up in a suit like at an interview (maybe someone disagrees) but look presentable as you need to make a good impression.
Body language is a big thing at interviews so try to be emotive with your face, smile etc