I use any service suitable for students like zoom, skype, microsoft teams, but usually I prefer discord for teaching. I study people usually for one hour two times a week in the evenings (in my time zone).
In my lessons I use additional tools like video experiments, simulation programs (PHET sims) or virtual whiteboards (Idroo, Miro and etc) to allow my students to write there with me.
I am always available for questions from my students in social media like whatsapp or telegram and despite taking price for usual lessons, I often also use social media to send homework and additional materials like available internet or youtube lessons if my student didn't get the topic, so they won't necessarily need additional lessons. In specific cases I also tutor particular math topics if student need this but don't teach math on a regular basis.
I am very open to feedback from parents and students themselves, as often as it is possible, so I can improve my approach individually for every student and will be very glad to see your feedback on this site too.