Boundaries

Know where the boundaries are for the space you're currently using, including where your own SIDES (and door mirrors) are heading.

Knowing these edges comes second to noticing how others nearby are moving. But it's generally more important than what others MIGHT do.

​And it’s certainly more important than most signs or markings, and signals.

To judge your position accurately, practise using ref points but being aware of perspective and parallax. (And don't ignore your personal boundaries for sleep, alcohol, noise, medication, and mood).