This short Ableton Live clip covers the four transport and view-switching shortcuts you'll use constantly: Spacebar to start playback, Shift+Space to resume from where you left off, Tab to toggle between Session and Arrangement View, and Shift+Tab to switch between Clip View and Track View in the Detail View at the bottom of the screen.
Knowing the difference between Spacebar and Shift+Space alone saves a lot of repositioning time, especially when you're mid-arrangement and need to check a specific moment without losing your place.