I have a Raleigh hybrid so I can sit up straight (ruptured disc in back). I ride a combination of bike trails and rural/urban roadways. I commute a couple of times a week....26 miles in one day. I start VERY early in the morning (4:00 am most days), and come home in late afternoon.
I have redundancy (X 3) in all of my front and rear lighting.....a primary handlebar mounted headlight consisting of a 20 watt halogen (flood), a supplemental handlebar mounted Xenon headlight with a combination/alternate flashing amber light that is visible 180 degrees, a 3 watt Luxeon LED helmet mounted headlamp (spot) that also has a flashing red led row of lights on the battery pack in the back, a clip on red led flasher that attaches to my backpack nicely, and finally a flashing red led light that is incorporated into my bike lock wrapped around my seatpost (not as bright as the clip on but is visible about 270 degrees).
I ride prepared. I have a backpack which carries extra tube, tire inflator, tools, raingear, fleece jacket and gloves in winter, water, food, etc. I also carry a small cannister of pepper spray for potential assailants (animal or human) as well as a high decibel alarm. I have a personal cell phone and a work cell phone, and a multitool all in a belt mounted pouch. I have sunglasses, sunscreen, and also a pair of clear safety glasses for the dark mornings if the bugs are bad.
I have Kevlar reinorced tires (great!) with standard tubes for easier pedaling, but use plastic liners and sealant. I haven't had a flat since I started commuting a couple of years ago (this in spite of living in a "Goathead USA" area).
My method of riding is assertive when necessary, but not aggressive. I ride the shoulder but not too far to the edge on a highway....my experience is most vehicles appreciate this and I rarely have any problems. The ones who don't would buzz you if you were close to the line, but generally won't come over onto the shoulder. In urban areas I ride on the less traveled roads and try to use trails where possible. I try to take different routes to mix things up, but always find the least congested ways to do them. If I have to be on a road with heavy traffic I find a way off as soon as possible. I will go out of my way to do so. I would rather ride a mile out of my way....but do it comfortably. I do run stop signs occasionally (esp. if turning right), but slow down to nearly a stop. I will not just blow across an intersection. I use the crossing signal buttons at stoplights....but always ride across.
On the trail I use a bell when approaching a slower bike or walkers.....rather than yelling "on your left". My experience has been most people prefer that sound and do not get as alarmed.....but is still very effective.
My philosophy is to do what it takes to feel secure when riding and still not be intimidated. Whenever possible, I defer to something larger than me regardless of the law or the rules of the road. I've found I ride with much less stress accordingly....and feel I've avoided many potential incidents with vehicles using that approach. I would rather be slightly inconvenienced and remain uninjured. Discretion being the part of valor or something to that effect...though I draw a distinction between being smart and being timid, and recognize that rules will not always save your life. I enjoy riding much more when I feel like the decisions I've made while riding have created a safer situation for myself (and anyone else I engage). For those who stubbornly insist on riding in accordance with every law and every rule 100% of the time, I salute you. But I typically assess each situation and act in proportion to the tenor of each scenario at the time. To me that is assertive.