The only tips i have seen is to prepare as if it was a face to face one. Don't sit on the sofa in your pyjamas, get dressed and sit at a table with your pen and notes, and you will feel more professional.
Stand up and walk around when you're taking, you'll be more animated and energetic than you would be if you were sat down. And smile, it does impact how your tone of voice comes across. And obviously made sure you're somewhere private with good phone coverage. Other than that, treat it like a normal interview and prepare like you normally would. It is tougher as you don't have visual cues from the interviewers to see how you're getting on. So be confident, don't give long answers and if in doubt ask if you've given them the information they're after. Good luck.
Practice. Same as any interview. Find generic interview questions and create proper answers. Have a couple of scenarios that can be adapted to each question if it's competency based. Don't use the same scenario for more than one or two questions. Write a list of bullet point prompts like you would bullet point your skills on your CV. Good luck Op