When marking off penalty yardage don't get in the habit of counting your steps. If a penalty occured at A's 37 and the ball was being moved back to A's 27 I'd count two steps to the 35, jog (as much as you could in 5 yards) to the 30 and then count off the remaining 3 yards. After pacing off the yardage I'd place the ball or move in to the harsh mark if required.
It's also a good idea to get your HL to pace off the yardage indepedently so you use his spot as a check to see if you agree. It's especially helpful when you start pacing off the yardage in the wrong direction.
