Preliminary Interaction with the Student

Reach out to your student with a greeting, and allow him or her to respond with aspirations for the lesson. It's possible you would like to further discuss the student's level and goals in the first lesson - that's fine, but doing an initial, "thanks for scheduling time with me, looking forward to it" kind of message pre-lesson will be appreciated by pretty much anybody. 

This isn't a necessity, but it is definitely a nice gesture. This also eases the path to a follow-up message after the lesson has been completed.

Engaging with the student outside of the face-to-face meeting is great. Of course you don't want to spend all your time supporting the student outside of a lesson - you're trying to make a living, after all, but so long as you are polite and responsive, the type of student you want to keep is one that will also appreciate having an open communication line with you for occasional out-of-lesson communications.

Finally, this kind of approach is very personality driven, so if you don't feel you want to engage with students outside of the lesson, that's fine too - this is just a suggestion.

Go to In the Lesson - Differences In Communicating With Online Music Lessons.