Sometimes a phone call is best
A phone call is best if your situation is unusual in some way, such as an unusual timeline due to sports, limited availability for tutoring, learning disability considerations, math course selection advice, etc.
The best time to call is weekday mornings.
Sometimes an email is best
Email is best if you have a simple inquiry, such as you want to know whether I tutor a particular course or standardized test, you want to know my availability, you want to know my rates, etc.