How do you manage your students day to day? WhatsApp, app, spreadsheet

Curious how other independent tutors handle the admin side of things.

A few questions:

• How do you schedule sessions with students? WhatsApp, email, some booking tool?
• How do you track payments and who still owes you money?
• Do you use any specific app for this or does everything go through WhatsApp/texts?
• How do you communicate with parents?
• Do you ever feel like you need a simple tool that pulls everything together in one place?

Not trying to sell anything — genuinely curious how others handle this before it becomes a mess.