This one seems obvious when you think about it, but I didn't even realize I was doing it. Which makes it a bad habit, and maybe worth reminding people about.

The situation: I'm coming up to my left turn, wide lanes and multiple lanes including dedicated turn lanes. The cars are queued up so I filter up to sit beside the first in line. There's plenty of room and I'm going to turn wide into the bike lane, pacing the lead car or just behind him, out of everyone's way. It works pretty well, when there's lots of room.

The light turns green, wait a couple of seconds for traffic to clear, the car on my left goes and I go. All good, right? Wrong, don't do that! As soon as we enter the intersection, we're slamming the brakes because some fool is shooting through the red - he must have been going 70. I have unusual reflexes which saved me, but thank God the driver on my left also stopped in time because his car wouldn't have been much of a "shield" if he'd been hit at that speed.

Always look first, even when other cars are already entering the left turn! When I'm in front, of course I look and I'm not going until I see them stop. But I just trusted the other driver in front, and I didn't realize consciously that I did until almost too late. Subconscious habit. Stay aware out there!