I commute 1-2 days a week, 22 miles round trip in phx, az, plus short-distance errands and visiting friends (within 3 miles), and more random pleasure riding in central phx. I plan to increase the days commuting to 2-3+ a week. The commute is mostly on quiet residential streets, or low speed limits, 25-35 mph, or sometimes along canals. I always wear helmet and gloves, flashing lights front and rear at night, with lights in front to see as well as be seen and lots of reflective stuff. Given my careful route selection (and good luck in the points A and B that I move between) I almost always ride in the street. When I have the slightest doubt, I shamelessly ease onto sidewalks or make left turns pedestrian-style. When moving cars are nearby, I wait at red lights and stop signs like any other schmuck. When absolutely alone, I adapt the law to move things along. I always decline the courtesy of car drivers who waive me through stop signs when they were there first, by planting my feet on the ground and looking away. I have a voice which projects though urban noise, and I've admonished--with all the eloquence I can muster--boorish louts in cars, after making a judgement about gun ownership and planning escape routes. I've been lucky and aware enough to evade careless drivers, so far; my closest calls have come from wrong-way road cyclists, or oblivious sidewalk cyclists (I work at a university, to put this in context.)
When I first bought a bike, two years ago (I'm of a certain age), it was just for the pure fun of riding. Gradually, it's replacing my car, mile by mile--even in the brutal summers here and despite phx's bike-unfriendly reputation.