Rotate the Velodyne by slowly rolling and pitching at the beginning of the scan before moving around.
When transitioning between rooms or turning corners, move a little slower to build up new area before proceeding.
Scanning with the lidar scan planes closer to horizontal is the best. Tilting up to 45 degrees is okay when stationary. Definitely do not combine tilting with rotations while scanning.
Do not start scanning in a corner or near a wall. It is better to start in the center of the room.
When ascending/descending stairs orient the sensor parallel to the pitch of the stairs (also see 1.a above).
For large areas, it is best to hold the scanner above your head to get the overall outline of the room. This will help eliminate any drift while walking around.
For vertical scanning, tilt the lidar up to 45 degrees while standing still, but do not tilt and move around at the same time.
While scanning vertically, ensure there is structure in front of and behind the scanner.