I keep my communication outside of in-person lessons directed toward the benefit of the student/parent. When I respond to an inquiry for tutoring, I normally mention that I will give a 15% discount at the start of the 25th hour in addition to the 15% discount Wyzant offers for buyers who purchase hours by the bulk. I communicate to students/parents when holiday times come that they may have an extra small discount to buy themselves a turkey. I offer them a small discount during Mardi Gras since parades traffic and unusual environmental activity makes travel less convenient. And somewhere in the timeframe of our lessons, I send an email to offer to augment in-person lessons with students who purchase just a few lessons with some pointers in any part of their topic they need. Each of these announcements receive a written message. I use the phone only by request and usually we coordinate our plans via emails. For accounting and AP courses, I request that I be sent pertinent documents in advance so that I can approach the first lesson with much of the anticipation that the student has.
Students send their preferences for meeting places, times, and description of their needs, and after that, I don't usually find much extraneous material from them. When I carried a cel phone, I received messages stating that that student was on the way or going to be a little late. But I quit carrying a cel phone and inform students of this fact.