Hyper-vigilance is key. Being visible only helps you if the motorist SEES you.
I assume all motorists are inattentive. That's the survivalist mentality.
Today I was riding a few inches shy of the line between the bike lane and the driving lane on 10th Avenue in Golden as I approached a cross street. I have reflective tape on my sleeves, a flashing light on my bike, I was riding in the most visible part of the roadway but the sun was behind me.
A truck pulled up to the intersection to cross in front of me. He had to stop, I didn't. I saw him look my way, but I saw the full sun on his face and I was moving into the shadow in front of him.
I knew he was going to. And he did. Even though he LOOKED right at me he didn't SEE me. And it really wasn't his fault.
I grabbed both brakes hard and yelled "HEY!" as I saw him surge forward to cross directly into me.
I stopped. He stopped. Crisis averted.
If I had not been cognizant of the situation, if I had been blundering down the street oblivious to the currents of traffic I would have been smashed across the grill of his truck. And honestly, expecting him to have seen me was asking a bit much. I was a small target with the sun behind me. Great if you're a fighter pilot, not so much if you're a bike commuter.
The event didn't even get my heart rate up. I saw it coming and acted accordingly. I try to always make eye contact with ANY motorist that may cross my path. If I can make eye contact and see that they see me I can plan accordingly. If they don't see me I assume they're going to act as if they don't know I'm there. It's saved my hide more times than I can count.
Hyper-vigilance should be requisite for all travelers upon the roadways, but more so for cyclists.