By default, LiteMount looks for a usable action in the following list (in this order), and stops when it first finds one:

1. Exit vehicle : if you are in a vehicle that can be exited.
2. Dismount : if you are mounted (includes cancelling Travel Form).
3. Copy target's mount : if target is a player, is mounted, and you know that mount.
4. Apply any Rules settings.
5. Mount a swimming mount : if you have been swimming for more than 1s and SHIFT is not held down.
6. Mount a flying mount : if you are in a flyable area and one is usable, and SHIFT is not held down.
7. Mount a ground mount : if one is usable.
8. Mount a slow ground mount : if one is usable.
9. If you are falling, try Slow Fall, Levitate, Glide, Zen Flight, Hearty Dragon Plume or Rocfeather Skyhorn Kite.
10. Run the "Unavailable" macro : if one is set.

If you are moving or falling it will only consider instant-cast mounts (Travel Form, Ghost Wolf, and (during Hallows End) Flying Broom).

You can use the Advanced Options panel to completely change this priority if you want.