I have found that having a good video chat system is super important. At first, my company used Google Hangouts, but we weren't happy with the video quality. A few systems later, we ended up with Zoom, which has been pretty good. They also integrate nicely with Slack, so that you can set it up such that the command "/zoom" in slack will start a new video chat room that people can click to join. A seamless video chatting experience is crucial for remote workers.