It is useful to know these VoiceOver gestures to activate/deactivate Screen Curtain, pause/resume VoiceOver, easily simulate a long press for opening context menus, or quickly move the cursor to the screen's first or last elements.

This is my favorite way of testing VoiceOver. Pick a flow in your app. Turn VoiceOver on. Triple tap with three fingers on the screen to enable Screen Curtain. The screen goes off but you can still navigate your device with VoiceOver.