The following chart summarises the many subtle ways in which different single models relate to the Movement rules when they are moving on their own. Where models are ranked into units, they follow the normal rules for unit movement, except for skirmishers, flyers and fast cavalry, which follow the rules detailed in their own sections.
Basically, single models move in two different ways, depending on their type (see chart below):
As Monsters: No need to turn or wheel - can pivot on the spot with no penalty but behave like units in all other respects (90° arc of sight, pay penalties for difficult terrain/obstacles and have clear flanks and rear).
As Skirmishers: No need to turn or wheel, can pivot on the spot with no penalty, 360° arc of sight for charges, etc, no penalties for difficult terrain/obstacles, will line up to formed units charging them and not vice versa, and do not have front/flanks/rear until engaged in close combat.
Single Model Movement Chart
Roughly man-sized; Square 20/25 mm base; On foot
Up to & including Ogre-sized;* Square 40/50 mm base; On foot
Monster (larger than Ogre-sized);** Any base/no base
Cavalry;*** 25 x 50 mm base
As monsters (may not march)
* Includes Swarms, Chaos Spawn, etc.
** Includes Great Eagles, Stegadons, Giants, etc.
*** Includes Chaos Hounds, Dire Wolves, etc.