Some key issues to consider when performing remote user testing:
Make sure to record the testing sessions. Sometimes you’ll get misleading comments when you ask users what they thought about their task. Watching test respondents’ behavior provides valuable additional insight into their true feelings and attitudes. It’s also important to have audio with your screen recordings so that you can analyze what the user says when they think aloud. Always tell users to use the Think Aloud protocol during testing so that you can understand why they’re doing what they’re doing on the user interface.
Additionally, remote user testing is no longer confined to desktops. Mobile and tablet prototypes are regularly needed in the testing of user interfaces, so the remote testing tool needs to allow for testing these prototypes as well.