A quick Ableton Live shortcut for working in the MIDI editor: select a note and hit Z to zoom in tight on it, then Shift-Z to zoom back out. Small move, but it keeps you from constantly scrolling and pinching to see what you're doing when placing or nudging notes.
Useful when you're fine-tuning timing or velocity on a dense MIDI part and need to see one note clearly without losing your place in the clip.