If you're not meeting your clients in person, then your options are limited: phone or videoconferencing.
The problem with videoconferencing is the competing standards. There's (deep breath): Skype, Facebook, FaceTime, Google Hangouts, WebEx, and more. Some are mobile-friendly, some are not. Some are great for Apple users, some are better for Windows users.
Your best bet is to be familiar with all the standards, just in case your client is a die-hard adherent to single platform. And if not, there is an up-and-coming cross-platform standard that is compatible with nearly everything.
Peacock Family Christmas
My family's Christmas morning is an example of what will inevitably happen with your clients:
Five siblings. More devices than we can count. And yet, we couldn't bring the California and Missouri gatherings together because nobody could remember their Skype passwords (you will, but your client might not) and there was a big Android-Apple split.
Solution No. 1: Jack of All Trades
Again, as the service provider, you should probably be familiar with all of these platforms. A MacBook can run every single one of those platforms easily -- you just need to have them installed and ready to go when a client calls.
Solution No. 2: Master of One
Our solution, and one that will work with nearly any client who has a functioning smartphone or webcam-enabled laptop with a Wi-Fi connection, is WebRTC. We talked about the new open-source standard last year when it was just an experiment, but it has come a long way since then.
Every browser, except two (Internet Explorer and Safari) supports WebRTC, a video-chatting protocol that requires no software and no logins. Microsoft is set to update Internet Explorer to support the standard soon, which means only the tiny fraction of the market that uses Apple's Safari browser will be left out. It's not hard to imagine Apple adding support too, now that everyone else is on board.
How do you use WebRTC? We fiddled around with vLine, which is as simple as going to the site and sharing the randomly generated link to your private video chat -- a chat that can support more than two participants. An alternative is Talky.io, which has a much more robust feature set, but which we haven't had the time to fully put through its paces.
The point is this: compatibility. Nearly any person, on any device, can pop into your free, on-the-fly video chat, without signing up for some annoying, closed-off service.