#1 - always communicate to drivers your intentions by signaling your turns. Even when you think you're alone on the road. I got lazy this morning and didn't.
#2 - always always always scan before moving laterally in the roadway. Even when you think you're alone on the road. I did scan left before I turned left and discovered I was being questionably but legally overtaken - well maybe they were speeding, but everybody does there. It was simple enough for me to hold my line and not turn into the car but I wasted most of my margin for error by failing to comply with rule #1.
No, three. Three important safe riding rules:
#3 - the habits you practice matter. Moving left on the bike trail to overtake a pedestrian? Scan left. Turning left from a left turn only lane with two lanes of oncoming traffic? Scan left. Moving right on the bike trail after overtaking a pedestrian? Scan right. The habit is the thing that can save your life when you're lazy.