Fog can be nasty further south here in the valley, and some mornings my ride to work is surreal, almost like I am pedaling in some other dimension. My approach is as follows:

• MagicShine 900 lumen light on the bars
• Magic Shine 1000 lumen light on the helmet
• Planet Bike swiveling Blinkey on the back of my helmet, flashing
• Planet Bike Turboflash on blink on the back
• Cheapy Fred Meyer checkout lane Chinese blinker, blinking, on the backpack
• A steady read on the back
• Lots of reflective tape
• Nerd reflectors on the spokes

I will run the two headlights on "Medium", or sometimes will run the helmet light on flash, the jury is still out on that.

My "foggy" ride is usually in the morning - trying to get to work by 0630 at the latest. That way I have minimized local traffic. I would not willingly ride at night in the fog - too many folks hurrying home from work or wherever - I really notice a difference in driver behavior between the ride early to work than later from work to home. But if it's foggy at go-home time, that's how I have to ride.

I really don't think you can have too much blink going on in the rear - the more visible you are from the danger direction the better.