Correct speed and plenty of oil, don't let them get dull and re-sharpen at the first signs of reduced cutting.
Never used a drill doctor and don't know if they grind well or not, always re-sharpened mine by hand and always grind a relief on the back side to help break up the chips.
Bristoe is dead on with the heat treatment, but can't ever remember the need to heat treat a drill to re-sharpen. But have done plenty of chisels and star drills like that.
Phil
