I don't completely agree with Sheldon on this. The front brake is the most powerful and useful. Use of the rear brake alone is to be avoided due to the danger of rear wheel lock and skid. But I find shorter stopping distances from high speed with both brakes, and less risk of overheating a rim. I've overheated a rim stopping from 35 mph with the front brake only. I apply both brakes in high-speed stops, but put more force on the front one. To slow from low speed or just to bleed off some speed, I'll use front brake only.
The other important technique for braking is to shift your weight rearward on the bike (so the rear wheel won't lose traction) and brace yourself properly with your arms almost straight in front of you and your weight low. Braking from the drops improves your weight balance and bracing ability.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72