Everyone knows you should never be late for a personal interview, and that still applies over video call. Test your audio and video beforehand.
Close the door and windows in your room. Shut off the TV down the hall. Silence your cell phone during your online interview.
Dressing professionally for an interview puts you in the mindset of the interview. Having on a business top and pajama bottoms may put you in a half-sleepy mindset.
If you are interviewing in a house with multiple people or pets, be sure to let everyone in the house know ahead of time that you will be in an interview while securing any animals away from your interview space.
Body language is an equally or more important part of interpersonal communication than just words.