After reading an article about phone interviews posted in a LinkedIn discussion, I realized that the only tip that you really need to know about a virtual (as opposed to face-to-face)  interview is this: prepare for the phone interview exactly the same way you would an in-person. It’s that simple.
“But what does that mean?” you ask. Well, for a phone interview:

• Have your examples ready –> just like in a f2f interview, you never know what situational question they will ask – I practice writing these out by hand to try and make them “stick” in the forefront of my thoughts. Glassdoor.com has real interview questions asked to applicants, so see what candidates for similar positions were asked
• Have questions ready for them. Do your homework on the job & on the company – ask strong questions so they know you took the time to do research (Glassdoor.com also has company information)
• Have something to drink at hand (except soda – belching is so uncool!)..I always bring water with me to interviews – some places are polite enough to offer it, others aren’t. I even had an experience when interviewers brought water for themselves, but not for me. Wow.
• Dress in a clean, work-suitable clothing. Although it may be tempting to dress in PJ’s for the phone call because “who’s going to know?”, dressing at least somewhat professionally will get your mind in a more business-like frame of reference.
• Have hard copies of work samples ready for discussion. Though THEY won’t see them, it will help you remember to bring up some examples of things you’ve done, or bring up interesting topics to discuss.
• Don’t belabor points – I find I repeat my answers because, as the article points out, there are no visual cues to indicate they got the point, so I emphasize it again to make sure they got it. To combat this, I say it once, and then perhaps turn the question back on them, “What methods do you consider best for handling a disruptive patron?”

Final thought: So what’s the difference between phone & f2f: I think the only big difference is that with a phone interview, you can get up and move around, which I would suggest doing because it helps dissipate nervous energy.