Scanning electron microscopes (SEMs) are incredibly versatile instruments for millimeter to nanometer scale imaging and measurements of size and shape. New methods to improve repeatability and accuracy have been implemented on the so-called Reference SEMs at the National Institute of Standards and Technology (NIST). These methods include: 1) very fast digital imaging and real-time corrective composition of SEM images, showing superiority over both traditional fast or slow image collection methods; 2) high-precision sample stage with laser interferometry, providing traceability and compensation for stage drift and vibration with sub-nanometer performance; and 3) contamination and charging mitigation through hydrogen and oxygen plasma cleaning. These new methods can be applied in other SEMS as well to realize quantitative scanning electron microscopy.