Two-Factor Authentication (2FA)
Enable Two-Factor Authentication on every service, and keep your device with you.
Enable FileVault to encrypt disk
Lock Your Desktop When You're Away.
Seperate browsers for different purposes
For example, I usually used two browsers(Chrome Stable and Chrome Canary). Chrome Stable for my personal use, I will install any Chrome plugin I want on this browser. Chrome Canary for company use, without any Chrome plugin installed.
Register SPF for your domain to detect forging sender addresses
Whenever we are using the software, some of them will collect your data. For example, search history.