The biggest problem is with riding without lights at night or around dusk or dawn.

I usually use 2 rear lights in case one fails (battery dies, light fails, etc). That sounds like overkill at first, until you realize that if the back light goes out - you won't know, because you can't see it. You'll be biking along and have no idea that you longer have a light in the back.

I'd say lights are the #1 thing.

great point on lights. I leave one on my rear rack and have one lashed to the back of my helmet. provides not only redundancy but one two vertical levels for visibility

I also have one of those lights in front that attaches to the spokes. helps with visibility from the side, as forward-facing lights aren't always clearly visible by cars about to turn into/onto you

I experience this quite often, and in many cases, the person is not even trying to stay in front of me! Instead, the person just rolls up to right in front of me at a light. I wait until we get through the intersection and there is a gap in traffic and I take the lane and pass the person. Then, at the next light, the person does the same thing. I pass them again just as before. And at the next light, here comes that person again. Over and over and over. If any of you are local to SF, this happens to me on Market St. all of the time, particularly because of how the lights are timed. Totally maddening.

As a year-round commuter in Boston for a number of years, here are some axioms I keep in mind as I ride:

Treat all parked cars like a gun, and assume they are loaded, with an occupant ready to exit. (And if you filter through traffic, watch out for opening doors on your left as well as right.)

Make yourself as visible as possible, and assume no one sees you.

When riding at night look for cars, not just headlights.

Then there's Jim's Law of the Road: No matter how well-paved and lightly traveled a road is, there will likely be an obstacle on your right as a car passes on your left. (Corollary, wear a rearview mirror).

Treat all cars as if they are trying to kill you. They are.

Use turn signals. Make eye contact when you are signaling a driver of a particular car. Don't be wimpy with your signals, be assertive, don't be afraid of directing traffic.

Speed is your friend. At 7 to 10 mph you are a sitting duck. At 20 mph you are a darting rabbit. The faster you ride, the more time cars behind you have to see you.

Keep track of right of way and yield when it is not yours. Always stop at traffic lights, but I find it is safer to blow through a stop sign before any cars get to it than do a legal stop and then have to play who has the right away once the cars also come to a stop. Also, I will run traffic lights if I don't have the weight to trigger a left turn signal and I am in the left turn lane. Assuming it is safe of course and there is no car around to trigger it for me.

In really busy intersections, don't be afraid to get off your bike and walk it across the street. As a pedestrian you trump all other right of ways.

When a fast road bike passes you, draft him. You will get across town much faster.

When approaching a traffic light/intersection where you intend to go straight and cars behind you may be turning right or moving to a right hand turn lane, I think it helps to quickly glance over your left shoulder and look behind you. The movement of your head helps to attract the attention of the driver hovering behind you; it also helps you gauge the "body language" of the car coming up to prevent the "right hook."

I think hand signals are great but there is not a generally accepted signal for "I'm going straight MF, so don't try and cut me off." And when making hand signals turning your head to the intended direction helps to indicate your intention.

I generally point forward, extending the arm in a bit of an arc to make the point. I do this whenever I enter a rotary and am not taking the first exit, which cars for some reason seem to assume I will do. Works for me so far.

Know your surroundings and limitations, Have fun, ride the bike, stay alive.

https://vimeo.com/7171146

The route you drive to work may not be the best way for you to BIKE to work. Don't be a stickler for the "RIGHT" way to do things. you may have to or want to, do things very differently in your environment than others do in theirs. Be flexible and adaptable. there may be times when riding on the sidewalk is a practical idea (for example).

Get a copy of Robert Hurst's The Art of Cycling: A Guide to Bicycling in 21st-Century America from your library or bookstore. He covers the points mentioned by the posters and a number of others. There are other books, but Hurst's book is one of those which is practical and not dogmatic. I'm a better cyclist for reading it.

If you like courses and one is in your area, the League of American Bicyclists offers courses and has some online materials.

Another frequently cited link is BicycleSafe.com

Some I haven't seen mentioned while scanning this list

1. Never leave home without a spare tube and pump

2. Never leave home without a lock. You never know when you might need to stop someplace or pop into a store for something.

3. Always make eye contact with any driver you are counting on to yield (any car approaching you making a left turn and any car in the center turn lane that might turn in front of you).

4. At traffic light corners with a dedicated right turn lane I generally scoot over one lane over to the left and stop right up on the cross walk so that cars approaching from behind can get past you to make a right turn.

5. When making left turns at huge crazy intersections with lots of lanes and especially left turn lights I sometimes ride at pedestrian pace in the crosswalks with the walk signal rather than daring a short left turn signal with lots of cars trying to squeeze through. But that's about the only instances that I'll use crosswalks or sidewalks. The other exception being some bridges where the sidewalk is the only safe place to be.

No amount of my disapproval is going to convince them and I don't have time to debate with them when passing. I just assume they are stupid or crazy and take the lane, moving closer to the relative safety of traffic, allowing them to hug the curb in their salmonic way.

I think a good rule of thumb is don't filter past a car that will pass you back in the next few blocks. So two cars at a stoplight, wait behind. Twenty cars queued up at a light, some of which are turning right and there are pedestrians for them to wait for, zip up the line of cars on the left side.

Seriously?

Usually I just do a head check, take the lane, and attempt to politely inform them that the other side is safer.

20-30 mph has a potential for lethality, if you want to talk lawsuit you should read up.
https://en.wikipedia.org/wiki/Last_clear_chance
https://en.wikipedia.org/wiki/Assault_(tort)

If this really gets your hackles up, how about a full stop instead of chicken?

A full stop is sufficient to force the salmon to deal with the situation they created. Also it's legal.

You might very well be right, but I'd like to believe that many of the salmon simply don't know what they're doing is wrong. With non-verbal communication (a look) you can comminicate your intentions to the other party and gauge their response without a more directly confrontational verbal exchange. I can tell that person I'm going through and see if they respond agressively, in which case I make other plans, or submit to my cue.

I'm definitely not going to stand on ceremony and play chicken with one who is being agressive towards me.

ah...I achieved Enlightenment today by following the advice of the Underwear Nazi. sooooo much better....

Not sure I go that close, but I know that if you ride too far to the right, it invites cars to try to pass you in the lane. Motorcycles are even worse at doing this. Twice I have been passed by motorbikes in the lane and had no idea how they got by or how close they came. Just happened that fast.