Here are my top 2 for now:
- Control N (or Command N on a Mac) to open a new window and, if you need that window to be in incognito mode, try Control Shift N (or Command Shift N on a Mac). Why would you need an incognito window? I use it all the time when I need to log in to my account on someone else's device or in the workroom and I don't want to have to sign them out. The best place I use it is when I am demonstrating something from a student account side of things. Then I can just go back and forth between my teacher account and the student view.
- Control Shift T (or Command Shift T on a Mac) This one is magic! How many times do you close a tab and realize "Oh darn, I need one more thing there and I have to go find that page again!" Control Shift T reopens that tab! Magic right?!