Coinhop. While I use My Music Staff for my invoicing and payment tracking, I do not connect it to Stripe for taking payments through the site. I prefer having all my clients make monthly payments set up with Coinhop. At only a 1% fee, it's much cheaper than Stripe or PayPal. Read more on my experience in this post: Save Time and Money Taking Online Payments With Coinhop.
Boomerang for Gmail. This Chrome extension helps me schedule emails to send at optimal times, snooze messages, and my favorite benefit - follow-up reminders if someone doesn't respond to your email.
Gmail. My email client. I like using the browser mail client instead of Outlook or Apple's Mail app.
Flodesk. My email list manager. After using Mailchimp for years and years, I have found Flodesk to be even more sleek, simplified, and user-friendly than Mailchimp.
Wisestamp. Generates professional, custom email signatures.
Google Forms. Google Forms are free and easy to use. Use it for studio registration forms as well as event sign-up forms. You can easily export the entries into a spreadsheet format.
Tally.so. Tally is another form builder I've been using in conjunction with Notion. It takes a little more tech-savvy work to connect the two, so if you shy away from tech, I recommend using Google Forms.
Studio Management Software
My Music Staff. My Music Staff is a studio-management cloud-based software. It does not have an app and is only available via your brows. While it has many robust features, I simply use it for sending invoices and tracking payments. I also use their form embedded form feature to connect student inquiries on my website to my student lead list in My Music Staff. Nicola Cantan highlights this latter feature in this blog post.
Vivid Practice. For online lesson assignments. I especially appreciate the simplicity of the design of this app. Attach sound files, links, and PDFs to every individual assignment.
Hosting / Website / Blogging
Hawkhost. I have been super happy with Hawkhost. Their client support has always been quick to respond and very helpful. They provide great service.
WordPress.org For those more comfortable with technology and looking for lots of customization possibilities. This website, as well as my studio website Studio88Piano.com, are both built-in WordPress.
Weebly.com For those less comfortable with technology, Weebly.com is a great way to go and will help you produce a great-looking website more easily.