If you want ultimate privacy in a computer, just go with Linux. That said, many people can't or choose not to. So here are some fast recommendations for making sure your Macbook is as private as possible. This is not comprehensive, so if anyone has more ideas that I can share with folks, please add them! Going to add this to my personal site, too.
(Also because I'm dorky, if you want to use this as a checklist, you can replace the ☑️ grayed out box with a ✅ when you accomplish it 😁 )
☑️ BROWSER - use Firefox and uBlock Origin for Mac, and choose a private search engine (DuckDuckGo - though beware, they are censoring; Mojeek; Brave; SearX; etc.); this will keep your identity private when it comes to fingerprinting and keep most sites and trackers from following your activity
☑️ VPN - Use a VPN when you are doing anything that you want private! If you use Proton for your email, it comes with Proton VPN. If you don't, Mullvad VPN is available for Mac, as well!
☑️ OFFICE SOFTWARE - if you need office software, I highly recommend LibreOffice. Apple and MSFT office software mine data now. Libre does not!
☑️ BACKUPS - I do not recommend using iCloud, nor do I recommend using Google Drive or a similar service. I would recommend using an affordable secure service, such as Internxt. https://internxt.com/drive or PCloud or Nextcloud (I like NextCloud a lot and I run it hosted locally on my home server.) Ideally you'd have multiple backup methods, so choose a cloud method and choose another hard copy method, like an external drive.
☑️ ANTIVIRUS - use a good antivirus, not the one that Apple provides. I recommend WebRoot - I used them for years and years until I switched to Linux. You can get keys for it discounted on kinguin.net
☑️ FILEVAULT - turn it on. This will encrypt everything on your computer and is built into the Security & Privacy section on your laptop
☑️ STEALTH MODE - turn it on. Prevents people from trying to access it from any network you're on
☑️ 2FA- use that for everything
☑️ SIRI - turn that sh*t off (remove improve Siri & dictation, remove Siri suggestions, remove sharing of any data with Apple period)
☑️ SPOTLIGHT - consider whether you need this or if you need to set up privacy folders that prevent it from searching certain documents. You can configure folders that aren't scanned by using the Spotlight Privacy area.
☑️ SHARING - limit your sharing options in System Preferences if you don't need them