Just to illustrate that there are better and worse ways to apply brakes, here's an example of a less-than-ideal way: I was biking on a borrowed bike and getting used to the brakes. The front brake lever was squishier than the rear. After skidding out and landing my hip on a stump, which lowered morale significantly for the next half-hour or so, I learned to give the front brake a harder squeeze to compensate for the squish. This was on a mountain trail and at the urging of my biking companion on that day.
So my question is this: How does one brake under certain circumstances? Are there times when all-front or all-rear braking makes sense, or is it always best to apply pressure somewhat evenly to both brakes, and are there different braking techniques on roads vs trails and such?