Backup Tools
Offsite Backup:
I use BackBlaze as my offsite backup provider. It's never given me an error and it was very quick and easy to setup. They primarily only backup files that you're using, so if you keep files in weird places (not the normal "Documents, Movies, Photos, Desktop, Dropbox" etc.), you'll probably want to look elsewhere. Versions of your files are kept for 30 days.
Local Backup:
Time Machine runs to back up active documents (and their changes) to a dedicated external hard drive. I have a task to connect it every 1-3 weeks. (Ideally, you would backup more frequently, but I found it unlikely that I will follow through any more often than that. If you have a desktop computer, you could just leave it connected all the time.)
Carbon Copy Cloner. This is how I make a copy of my Mac that I can just boot up and go if something horrible happened to my laptop. Again, to a dedicated hard drive. I'm not comfortable admitting how frequently I actually run this, but ideally at least once per month. Hard core backup people often run this weekly, or even nightly.
This is great to run before you install a new operating system, though you might want to keep a copy on a drive that isn't your regular clone drive-- just in case there's some mission critical software you can't run in the new OS.
Coaching Tools
Scheduling:
Acuity is my first line of defense in scheduling client meetings. I also run very wacky workflows in the Workflow app on my iPhone to create all the tasks and additional calendar items I like to have around a client meeting.
Website Tools:
SquareSpace for managed hosting (simpler). Or Dreamhost for more extensive needs. Hover for just domain names.
Don't like tricky business model with GoDaddy and Wix
Credit card processing/billing:
Don't be personally responsible for holding on to credit cards of your clients, and never ask them to send information like social or credit card info over email.
Mac Utilities:
Use your Mac better and more fluidly with some fun Mac Utilities that I love.
Better Resize Tool